Double telescopic stand column of hydraulic support

Abstract

The present application relates to the technical field of hydraulic support supporting technology, and more particularly to a double telescopic column of a hydraulic support. The double telescopic column comprises a large cylinder, a middle cylinder and a movable column which are sequentially sleeved. The middle cylinder is provided with a middle cylinder piston which separates the inner cavity of the large cylinder into a lower cavity of the large cylinder and an upper cavity of the large cylinder. The movable column is provided with a movable column piston which separates the inner cavity of the middle cylinder into a lower cavity of the middle cylinder and an upper cavity of the middle cylinder. The lower part of the large cylinder is provided with a lower cavity liquid inlet, and the upper part of the large cylinder is provided with a first upper cavity liquid inlet. Meanwhile, the movable column head is provided with a second upper cavity liquid inlet, and the movable column is provided with a first deep hole which is arranged in the axial direction and is communicated with the second upper cavity liquid inlet, and the first deep hole is communicated with the upper cavity of the middle cylinder. Through the second upper cavity liquid inlet arranged on the movable column, the column can realize double-channel liquid inlet when the column is lowered, effectively avoiding the problem that the single-channel liquid inlet leads to single pressure relief channel and easy local liquid resistance. Meanwhile, the deep hole liquid inlet channel in the movable column is further optimized to further optimize the liquid transmission path.

Description

Technical Field

[0001] This invention relates to the field of hydraulic support technology for mining, and in particular to a double telescopic column of a hydraulic support. Background Technology

[0002] The uprights in a hydraulic support are the core load-bearing components, primarily bearing the roof load and connecting the roof beam to the base. Their performance directly determines the support strength, stability, and overall reliability of the hydraulic support. Currently, the uprights used in fully mechanized coal mining faces are mainly single-telescopic, double-telescopic, and triple-telescopic uprights. Among these, double-telescopic uprights are the most common type in coal mine hydraulic supports. The telescopic ratio of double-telescopic uprights is suitable for most coal seams, and they offer advantages in both cost and performance; therefore, most coal mine supports adopt double-telescopic uprights.

[0003] With the continuous advancement of coal mining technology and the increasing depth and intensity of mining, especially to meet the demands of high-extraction working faces, double telescopic columns need to withstand increasingly greater working resistance. This increases the stress on support components, and excessive pressure can lead to instability in the hydraulic system, even causing hydraulic failure or safety accidents. It also places higher demands on the structure and selection of seals. Traditional double telescopic columns typically consist of a three-stage assembly of a large cylinder, a medium cylinder, and a piston, relying on hydraulic oil to extend each stage of the cylinder to complete the designated action. During column descent, smooth descent often relies on back pressure or valve group control of the hydraulic system. When the hydraulic system malfunctions or in an emergency, traditional pressure relief methods have a slow response time and are prone to generating impact forces. Furthermore, to achieve greater working resistance, it mainly relies on increasing the cylinder diameter. However, simply increasing the cylinder diameter is not only strictly limited by underground space and support weight, but also causes significant impact on the column when the roof pressure is too high. Excessive internal pressure in the secondary cylinder still poses a significant safety hazard. As the main pressure-bearing component of the hydraulic support, the column is under constant high pressure. The rapid loading of the top plate and the impact pressure results in insufficient pressure peak reduction. Although the safety valve is used for pressure limiting, the cylinder lacks a dedicated pressure-reducing structure, limiting the effective pressure-bearing area. Under the same support resistance, the system working pressure is too high, which exacerbates seal wear and pipeline fatigue. The cylinder may expand and the support may become unstable, which can easily lead to frequent liquid spraying and downtime for maintenance.

[0004] Therefore, there is an urgent need for a double telescopic column that can effectively balance the internal working pressure of the column, achieve smooth lifting and lowering, and has a long service life. Summary of the Invention

[0005] (a) Technical problems to be solved

[0006] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a double telescopic column for a hydraulic support, which solves the problems of single-channel liquid inlet, slow pressure release, easy generation of local hydraulic resistance, excessive internal pressure of the column, poor coordination of the column lowering process, and safety hazards caused by the traditional double telescopic column.

[0007] (II) Technical Solution

[0008] To achieve the above objectives, the main technical solutions adopted by the present invention include:

[0009] This invention provides a double telescopic column for a hydraulic support, comprising a large cylinder, a middle cylinder, and a piston, which are axially slidably fitted together from the outside in. A piston, sealing against the inner wall of the large cylinder, is located on the outer peripheral wall near the bottom of the middle cylinder, dividing the inner cavity of the large cylinder into a lower chamber and an upper chamber. Similarly, a piston, sealing against the inner wall of the middle cylinder, is located on the outer peripheral wall near the bottom of the piston, dividing the inner cavity of the middle cylinder into a lower chamber and an upper chamber. The lower part of the large cylinder has a lower chamber inlet connected to the lower chamber, and the upper part has a first upper chamber inlet connected to the upper chamber. The bottom of the middle cylinder has a bottom valve capable of selectively connecting the lower chamber of the large cylinder and the lower chamber of the middle cylinder.

[0010] The piston rod has a second upper chamber inlet on its head, and the piston rod has a first deep hole that is axially arranged and connected to the second upper chamber inlet. The first deep hole is connected to the upper chamber of the middle cylinder.

[0011] Optionally, the piston rod has two interconnected second upper chamber inlets, one of which is equipped with a safety valve, and the other is used to connect to an external hydraulic system.

[0012] Optionally, a first through hole is provided on the piston rod near the piston rod piston, extending radially and communicating with the first deep hole. The first through hole communicates the upper cavity of the middle cylinder with the inner cavity of the piston rod.

[0013] Optionally, two first deep holes and two first through holes are provided around the axis of the piston rod, with each first deep hole and each first through hole corresponding to one another.

[0014] Optionally, the device also includes a pressure-reducing rod, which is slidably inserted into the inner cavity of the piston along the axial direction. Its bottom end is fixedly connected to the bottom of the intermediate cylinder, and its top end has a piston portion that seals against the inner cavity of the piston. The piston portion divides the inner cavity of the piston into a lower piston cavity and a pressure-bearing cavity. The pressure-reducing rod has a second deep hole extending axially and a third deep hole extending radially. The second and third deep holes communicate with each other, and the third deep hole is located near the bottom of the lower cavity of the intermediate cylinder. The second deep hole communicates with the pressure-bearing cavity, and the third deep hole communicates with the lower cavity of the intermediate cylinder.

[0015] Optionally, the pressure-reducing rod is simultaneously fixed to the cylinder bottom of the intermediate cylinder block using a connecting plug and a locking screw. At the center of the cylinder bottom of the intermediate cylinder block, a first mounting hole adapted to the connecting plug is provided, through which the connecting plug is screwed onto the end of the pressure-reducing rod. A second mounting hole adapted to the locking screw is provided on the connecting plug, through which the locking screw is screwed onto the end of the pressure-reducing rod.

[0016] Optionally, the connecting plug is provided with a second through hole extending axially and a third through hole extending radially, the second through hole and the third through hole communicating with each other. The second through hole communicates with the second deep hole, and the third through hole communicates with the third deep hole.

[0017] Optionally, two of each of the second deep hole, third deep hole, second through hole, and third through hole are provided around the axis of the pressure reducing rod, and each of the second deep hole, third deep hole, second through hole, and third through hole is provided in a one-to-one correspondence.

[0018] Optionally, a middle cylinder guide sleeve assembly is provided on the inner side of the upper cavity end of the large cylinder body, a piston guide sleeve assembly is provided on the inner side of the upper cavity end of the middle cylinder body, and a pressure reducing rod guide sleeve assembly is provided on the inner side of the lower cavity end of the piston.

[0019] Optionally, at least two bottom valves are provided at circumferential intervals along the bottom of the cylinder block.

[0020] (III) Beneficial Effects

[0021] The beneficial effects of this invention are:

[0022] This invention discloses a double telescopic column for a hydraulic support. By providing a second upper chamber inlet on the piston column, the column can achieve dual-channel fluid intake during descent. This effectively avoids the problems of single-channel fluid intake, such as a limited pressure relief channel, slow pressure release, potential localized hydraulic resistance, and poor coordination during descent. Simultaneously, the deep-hole fluid intake channel inside the piston column further optimizes the fluid transmission path, allowing the high-pressure fluid entering the deep hole to undergo pressure transmission and gradual depressurization over a certain period. This avoids sudden pressure increases or excessively rapid impacts, reducing pressure in the piston column and the central cylinder during descent and improving the descent response speed. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of Embodiment 1 of a hydraulic support with double telescopic columns of the present invention (column retracted state).

[0024] Figure 2 for Figure 1 Schematic diagram of the double telescopic column (live column in half-extended state);

[0025] Figure 3 for Figure 1 A magnified view of the position of the capital column in the image;

[0026] Figure 4 This is a schematic diagram of a second embodiment of a hydraulic support with a double telescopic column (column retracted state).

[0027] Figure 5 for Figure 4 Schematic diagram of the double telescopic column (live column in half-extended state);

[0028] Figure 6 for Figure 4 A partial enlarged view of the connection point between the middle pressure relief rod and the middle cylinder block;

[0029] Figure 7 for Figure 4 A schematic diagram of the overall structure of the pressure-reducing rod.

[0030] [Explanation of Labels in the Attached Image]

[0031] 1: Main cylinder body; 11: Lower chamber of the main cylinder; 12: Upper chamber of the main cylinder; 13: Liquid inlet of the lower chamber; 14: Liquid inlet of the first upper chamber;

[0032] 2: Cylinder block; 21: Cylinder piston; 22: Lower chamber of cylinder; 23: Upper chamber of cylinder; 24: Bottom valve;

[0033] 3: Piston; 31: Piston piston; 32: Second upper chamber inlet; 33: First deep hole; 34: Safety valve; 35: First through hole; 36: Lower chamber of piston; 37: Pressure chamber;

[0034] 4: Pressure reducing rod; 41: Piston section; 42: Second deep hole; 43: Third deep hole;

[0035] 5: Connecting screw plug; 51: Second through hole; 52: Third through hole; 53: Annular buffer groove;

[0036] 6: Anti-loosening screws;

[0037] 7: Cylinder guide sleeve assembly;

[0038] 8: Piston guide sleeve assembly;

[0039] 9: Pressure reducing rod guide sleeve assembly; 91: Retaining sleeve; 92: Snap ring; 93: Dynamic seal;

[0040] 10: Threaded sleeve; 101: Retaining ring. Detailed Implementation

[0041] To better explain and facilitate understanding of the present invention, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments. In this document, the terms "upper cavity" and "lower cavity" refer to, according to conventional practice in the art, the end closer to the piston head being called the "upper cavity," and the end closer to the cylinder bottom being called the "lower cavity."

[0042] 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.

[0043] Example 1:

[0044] The uprights in a hydraulic support are the core load-bearing components, primarily supporting the roof load and connecting the top beam and the base. Double telescopic uprights have an extension ratio suitable for most coal seams and offer advantages in both cost and performance; therefore, most coal mine supports utilize double telescopic uprights. During use, at the location to be supported in the roadway, the double telescopic uprights are raised to their extended state, firmly supporting the top rock (roof) of the coal mine roadway. If it is necessary to move the hydraulic support to another support location, the uprights must be lowered. However, during operation, when the roof pressure is too high, the uprights will experience significant impact, leading to excessively high internal pressure in the secondary cylinder. Especially during the lowering process, localized hydraulic resistance within the cylinder further increases the internal pressure, severely affecting the coordination of various parts during the lowering process and posing a significant safety hazard. Therefore, referring to… Figure 1 and Figure 2 This embodiment proposes a double-telescopic column for a hydraulic support, comprising a large cylinder 1, a middle cylinder 2, and a piston 3, which are slidably fitted together axially from the outside in. Specifically, the middle cylinder 2 is slidably inserted into the large cylinder 1, and the piston 3 is slidably inserted into the middle cylinder 2. In other words, the "double telescopic" structure of the column is achieved by the telescopic movement of the middle cylinder 2 within the large cylinder 1, combined with the telescopic movement of the piston 3 within the middle cylinder 2.

[0045] A piston 21 is mounted on the outer peripheral wall of the middle cylinder body 2 near its bottom. The outer peripheral wall of the piston 21 seals against the inner wall of the large cylinder body 1, dividing the inner cavity of the large cylinder body 1 into a lower chamber 11 and an upper chamber 12. This achieves reliable sealing and pressure isolation between the two chambers, preventing high-pressure liquid from crossing and causing operational failure. Here, the terms "lower chamber 11" and "upper chamber 12" refer to their positional relationship: the lower chamber 11 is below the piston 21, and the upper chamber 12 is above it. This does not imply that the lower chamber 11 and upper chamber 12 are located in absolute positions within the large cylinder body 1. As the piston 21 moves, the specific positions and sizes of the lower chamber 11 and upper chamber 12 will change accordingly, but the lower chamber 11 will always be located below the upper chamber 12.

[0046] Similarly, a piston 31 is provided on the outer peripheral wall of the piston 3 near its bottom. The outer peripheral wall of the piston 31 seals against the inner wall of the cylinder body 2, dividing the inner cavity of the cylinder body 2 into a lower cylinder chamber 22 and an upper cylinder chamber 23. This allows the piston 3 to extend and retract independently under hydraulic drive, ensuring the normal operation of the column. Here, the lower cylinder chamber 22 and the upper cylinder chamber 23 refer to their positional relationship. The lower cylinder chamber 22 is below the piston piston 31, and the upper cylinder chamber 23 is above the piston piston 31. This does not limit the absolute positions of the lower cylinder chamber 22 and the upper cylinder chamber 23 in the cylinder body 2. As the piston piston 31 moves, the specific positions and sizes of the lower cylinder chamber 22 and the upper cylinder chamber 23 will also change, but the lower cylinder chamber 22 is always located below the upper cylinder chamber 23.

[0047] Preferably, the piston 21 of the middle cylinder and the middle cylinder body 2 are integrally formed. A combined stepped sealing ring is embedded on the outer peripheral wall of the piston 21. The combined stepped sealing ring is composed of multiple stepped sealing rings to form a continuous sealing step. Each step gradually reduces the medium pressure through a small gap or contact surface, reducing the load on a single point seal and improving the overall sealing reliability.

[0048] The piston 31 and piston 3 are also integrally formed (i.e., the plunger, piston tube, and piston head are integrally formed), and a combined stepped sealing ring is also embedded on the outer peripheral wall of the piston 31. The piston 3 can be manufactured using an integral forging process, with the entire structure forged and then precision machined to avoid welds between the separate structures, preventing weld failure due to the effects of ultra-high pressure liquid, and improving the service life of the column. Compared with the traditional separate structure, this reduces the high-precision machining requirements required for the fit between parts, and also reduces the use of seals, avoiding leakage problems caused by seals under high pressure. This fundamentally reduces potential failure points, improves the overall service life of the column, and effectively reduces processing costs.

[0049] A lower chamber inlet 13, connected to the lower chamber 11 of the large cylinder body 1, is provided at the lower part of the cylinder body 1 for supplying fluid to the lower chamber 11 during column raising. A first upper chamber inlet 14, connected to the upper chamber 12 of the large cylinder body 1, is provided at the upper part of the cylinder body 1 for supplying fluid to the upper chamber 12 during column lowering. The other ends of both the lower chamber inlet 13 and the first upper chamber inlet 14 are used to connect to an external hydraulic system. The two inlets are independently arranged to avoid fluid supply interference. At the same time, a one-way valve and a damping orifice can be installed in the first upper chamber inlet 14 to achieve controllable column lowering speed and prevent impact caused by rapid retraction.

[0050] A bottom valve 24 is provided at the bottom of the middle cylinder 2, which can selectively connect the lower chamber 11 of the large cylinder and the lower chamber 22 of the middle cylinder to achieve staged extension and retraction control of the column. This can be understood as follows: the lower chamber inlet 13, the lower chamber 11 of the large cylinder, the bottom valve 24, and the lower chamber 22 of the middle cylinder are sequentially connected to form the column lifting oil inlet circuit; the first upper chamber inlet 14 and the upper chamber 12 of the large cylinder are connected to form the first column lowering oil inlet circuit. To improve flow capacity and response speed, at least two bottom valves 24 are provided circumferentially at the bottom of the middle cylinder 2. In this embodiment, two bottom valves 24 are provided, which doubles the flow rate compared to a single bottom valve structure, allowing for faster pressure build-up and effectively improving the efficiency of the column lifting and retraction, preventing jamming during extension and retraction. Furthermore, a conical buffer surface is formed at the valve port of the bottom valve 24, allowing for gradual flow interception when the bottom valve 24 is closed, eliminating water hammer effect and protecting the valve seat and cylinder bottom structure.

[0051] Furthermore, referring to Figure 1 and Figure 3On the head of the piston rod 3, a second upper chamber inlet 32 ​​is provided, and a first deep hole 33 is also provided on the piston rod 3 along the axial direction. One end of the second upper chamber inlet 32 ​​is used to connect to an external hydraulic system for fluid supply, and the other end is connected to the upper end of the first deep hole 33. The lower end of the first deep hole 33 is connected to the upper chamber 23 of the middle cylinder. This forms an independent fluid supply channel inside the piston rod 3, used to supply fluid to the upper chamber 23 of the middle cylinder when the piston rod is lowered. That is to say, when the piston rod is lowered, there are two fluid supply ports, the first upper chamber inlet 14 and the second upper chamber inlet 32, forming a dual fluid supply channel. The deep hole fluid inlet in the inner wall of the piston rod can, on the one hand, disperse the fluid inflow path and shorten the fluid transmission path, reduce hydraulic resistance, and improve the lowering response speed without the need for a step-by-step pressurization transmission process; on the other hand, it allows high-pressure fluid to enter the preset channel (first deep hole 33) inside the piston rod 3, and the inflowing fluid can undergo pressure transmission and gradual depressurization inside the piston rod for a certain period of time, avoiding instantaneous pressure increase or excessively rapid impact. Considering the stress distribution of the piston 3 under high-pressure liquid, and based on simulation mechanics calculations, the diameter of the first deep hole 33 on the piston 3 is preferably φ8mm to minimize stress concentration. Traditional single-upper-cavity liquid supply methods suffer from a single pressure relief channel, slow pressure release, and are prone to localized liquid resistance and poor coordination during the column lowering process, making them unsuitable for use under complex load conditions with dual telescopic columns. Therefore, in this embodiment, liquid is simultaneously introduced through the first upper-cavity inlet 14 and the second upper-cavity inlet 32, fundamentally improving the high-pressure liquid introduction conditions. This dual-channel independent liquid supply significantly enhances the column's response speed and improves the internal pressure distribution within the column.

[0052] To further enhance safety redundancy, two interconnected upper chamber inlets 32 are provided on the head of the piston rod 3. A safety valve 34 is installed at either of these inlets, while the other inlet is used to connect to an external hydraulic system for fluid supply, ensuring that the internal pressure of the piston rod 3 remains within a safe range. When the pressure in the upper chamber exceeds the limit, the safety valve 34 can quickly release pressure, preventing risks such as cylinder expansion and seal rupture. The dual-port layout also prevents a single port blockage from causing a safety accident, protecting personal safety and ensuring stable equipment operation. This safety valve 34 can adopt a pilot-operated, high-flow structure with a pressure relief response time ≤0.1s, rapidly reducing pressure peaks caused by shock pressure.

[0053] See also Figure 3A first through hole 35 extending radially is provided on the piston rod 3 near the piston piston 31. This first through hole 35 connects to the first deep hole 33 and connects the upper chamber 23 of the cylinder to the inner cavity of the piston rod 3, allowing high-pressure liquid to enter the inner cavity of the piston rod 3 to participate in pressure reduction. In other words, the second upper chamber inlet 32, the first deep hole 33, the upper chamber 23 of the cylinder, the first through hole 35, and the inner cavity of the piston rod 3 are sequentially connected, forming the second inlet oil passage for lowering the piston rod. In this embodiment, two first deep holes 33 and two first through holes 35 are axially spaced around the axis surrounding the piston rod 3, with each first deep hole 33 and first through hole 35 corresponding one-to-one, to achieve uniform distribution of high-pressure liquid, reduce local hydraulic resistance and pressure fluctuations, and make pressure release more stable. Of course, this is not limited to this; depending on the internal pressure of the piston rod and the pressure relief requirements, multiple sets of first deep holes 33 and first through holes 35 can be provided, such as 3 or 4 sets. Furthermore, a replaceable throttling plug is preferably provided in the first through hole 35 to adjust the flow area according to the operating conditions, thereby achieving adaptive adjustment of the pressure reduction intensity.

[0054] Furthermore, to ensure smooth extension and retraction of the column and avoid jamming and shaking, a middle cylinder guide sleeve assembly 7 is provided on the inner side of the upper cavity end of the large cylinder 1 to guide and seal the extension and retraction of the middle cylinder 2. A piston guide sleeve assembly 8 is provided on the inner side of the upper cavity end of the middle cylinder 2 to guide and seal the extension and retraction of the piston 3, ensuring the coaxiality of the piston 3's extension and retraction. The use of multiple guide sleeves effectively prevents jamming and uneven wear during the extension and retraction of the column, effectively extending the overall service life of the column.

[0055] The working process of the double telescopic column shown in this embodiment is briefly described below:

[0056] The process of raising the column:

[0057] High-pressure liquid enters the lower chamber 11 of the large cylinder through the lower chamber inlet 13, pushing the middle cylinder 2 to extend upwards;

[0058] After the middle cylinder 2 reaches the set stroke, the bottom valve 24 opens, and high-pressure liquid enters the lower chamber 22 of the middle cylinder, pushing the piston 3 upward until the designed stroke is reached, completing the lifting action.

[0059] The process of column reduction:

[0060] High-pressure liquid enters the upper chamber 12 of the large cylinder through the first upper chamber inlet 14, and simultaneously enters the upper chamber 23 of the middle cylinder and the inner cavity of the piston 3 through the second upper chamber inlet 32 ​​and the first deep hole 33. The dual-channel liquid inlet drives the middle cylinder 2 and the piston 3 to retract synchronously. During the retraction process, the bottom valve 24 opens, and some of the high-pressure liquid flows back to the external hydraulic system from the lower chamber inlet 13. The first upper chamber inlet 14 and the second upper chamber inlet 32 ​​can also be supplied separately in stages to achieve staged retraction; this can be freely adjusted according to actual needs.

[0061] The dual telescopic column shown in this embodiment, through the second upper chamber inlet 32 ​​set on the piston 3, enables dual-channel liquid intake during column lowering. This effectively avoids the problems caused by single-channel liquid intake, such as a single pressure relief channel, slow pressure release speed, easy generation of local liquid resistance, and poor coordination of the column lowering process. At the same time, in conjunction with the deep hole liquid intake channel inside the piston 3, the liquid transmission path is further optimized, allowing the high-pressure liquid entering the deep hole to undergo pressure transmission and gradual pressure reduction over a certain period of time. This avoids instantaneous pressure increase or excessively rapid impact, which not only reduces the pressure in the piston 3 and the middle cylinder 2 during column lowering but also improves the response speed of column lowering.

[0062] Example 2:

[0063] Reference Figure 4 and Figure 5 The present embodiment proposes a double telescopic column for a hydraulic support, which differs from the embodiment 1 in that a pressure-reducing rod 4 is provided through the inside of the movable column 3. The rest of the parts are the same as the embodiment 1, so they will not be described in detail here.

[0064] Specifically, the pressure-reducing rod 4 is slidably inserted into the inner cavity of the piston rod 3 along the axial direction, with its bottom end fixedly connected to the bottom of the cylinder body 2. A pressure-reducing rod guide sleeve assembly 9 is provided on the inner side of the lower cavity end of the piston rod 3 to precisely guide the relative movement between the piston rod 3 and the pressure-reducing rod 4, further ensuring the stability of the piston rod 3 during extension and retraction. At the position where the bottom end of the pressure-reducing rod guide sleeve assembly 9 connects to the piston piston 31, a retaining sleeve 91 and a retaining ring 92 are provided. The retaining sleeve 91 is fixed to the end of the guide sleeve assembly 9 by bolts, and the retaining ring 92 is engaged with the inner circumferential wall of the piston piston 31 and abuts against the outer circumferential wall of the retaining sleeve 91. This retaining ring 92 can withstand a large axial force, precisely fixing the piston position and achieving a reliable structural connection. The top end of the pressure-reducing rod 4 has a piston part 41 that seals against the inner cavity of the piston rod 3. The piston section 41 and the pressure-reducing rod 4 preferably adopt an integral molding structure, eliminating the need for a static seal to withstand ultra-high pressure between the piston section 41 and the pressure-reducing rod 4. A combined stepped sealing ring is then embedded on the outer peripheral wall of the piston section 41, significantly improving the overall sealing reliability at the pressure-reducing rod 4. Due to the sealing fit between the piston section 41 and the inner cavity of the piston rod 3, the piston section 41 divides the inner cavity of the piston rod 3 into a lower piston cavity 36 and a pressure-bearing cavity 37, thereby increasing the effective pressure-bearing area to achieve pressure reduction.

[0065] The pressure-reducing rod 4 has a second deep hole 42 extending axially and a third deep hole 43 extending radially. The second deep hole 42 and the third deep hole 43 are interconnected, and the third deep hole 43 is located near the bottom of the lower cavity 22 of the intermediate cylinder. The second deep hole 42 connects to the pressure-bearing cavity 37, and the third deep hole 43 connects to the lower cavity 22 of the intermediate cylinder, together forming an independent pressure-reducing flow channel. High-pressure liquid enters the pressure-bearing cavity 37 from the lower cavity 22 of the intermediate cylinder through the third deep hole 43 and the second deep hole 42, transferring part of the load borne by the intermediate cylinder 2 to the pressure-bearing cavity 37. According to the principle of P=F / A, under the same support resistance, the working pressure of the secondary cylinder can be reduced by more than 20%, significantly reducing seal wear and cylinder fatigue.

[0066] In this embodiment, the lower chamber inlet 13, the lower chamber of the large cylinder 11, the bottom valve 24, the lower chamber of the middle cylinder 22, the third deep hole 43, the second deep hole 42, and the pressure chamber 37 are sequentially connected to form the lifting column inlet oil circuit; the first upper chamber inlet 14 and the upper chamber of the large cylinder 12 are connected to form the lowering column first inlet oil circuit; the second upper chamber inlet 32, the first deep hole 33, the first through hole 35, the upper chamber of the middle cylinder 23, and the piston lower chamber 36 are sequentially connected to form the lowering column second inlet oil circuit.

[0067] To ensure the reliability of the connection of the pressure-reducing rod 4 and to prevent it from loosening and falling off due to long-term vibration and impact. Figure 6As shown, the pressure-reducing rod 4 is simultaneously fixed to the cylinder bottom of the intermediate cylinder 2 using a connecting plug 5 and a locking screw 6, achieving double fixation. A first mounting hole is provided at the center of the cylinder bottom of the intermediate cylinder 2, the size of which is adapted to the connecting plug 5. The connecting plug 5 passes through the first mounting hole and is threaded onto the end of the pressure-reducing rod 4. Then, a second mounting hole is provided on the connecting plug 5, the size of which is adapted to the locking screw 6. The locking screw 6 passes through the second mounting hole and is again threaded onto the end of the pressure-reducing rod 4. This double fixation method using the connecting plug 5 and the locking screw 6 ensures a tight connection between the pressure-reducing rod 4 and the intermediate cylinder 2, preventing displacement of the pressure-reducing rod 4 during operation and ensuring the long-term stability of the pressure-reducing effect and the overall system stability. Furthermore, to facilitate the installation and positioning of the connecting plug 5, the first mounting hole is a three-step hole that penetrates the intermediate cylinder 3 and gradually narrows in diameter. During installation, the head of the connecting plug 5 is engaged at the third step. After the connecting plug 5 and the anti-loosening screw 6 are tightened, a retaining ring 101 is set at the end of the connecting plug 5, and a threaded sleeve 10 is screwed into the first mounting hole (that is, the threaded sleeve 10 is fixed at the position of the first step and the second step). The threaded sleeve 10 presses the retaining ring 101 to prevent the pressure reducing rods 4 from axial movement and radial displacement, thereby improving the long-term operational reliability of the column.

[0068] Preferably, an annular buffer groove 53 is provided at the bottom of the connecting plug 5. The annular buffer groove 53 communicates with the second deep hole 42 to form a buffer cavity, which is used to prevent hydraulic shock when the bottom valve 24 is closed, and at the same time to prevent the threads at the connecting plug 5 from loosening.

[0069] Further, see Figure 4 and Figure 7 The connecting plug 5 has a second through hole 51 extending axially and a third through hole 52 extending radially, which are interconnected. The second through hole 51 connects to the second deep hole 42, and the third through hole 52 connects to the third deep hole 43, forming a smooth pressure reduction channel. In this embodiment, two of each of the second deep hole 42, third deep hole 43, second through hole 51, and third through hole 52 are provided around the axis of the pressure reducing rod 4, and each of these holes corresponds to a specific hole, further increasing the flow area, reducing pressure loss, and improving pressure reduction efficiency. Of course, this is not a limitation; the number of the second deep hole 42, third deep hole 43, second through hole 51, and third through hole 52 can be set in multiple groups according to actual flow and pressure requirements, such as three or four groups evenly distributed circumferentially. Those skilled in the art can adjust this according to actual needs.

[0070] In this embodiment, the axial and radial double deep hole design on the pressure reducing rod 4 alters the fluid flow path inside the piston rod 3 and increases the fluid velocity, thereby reducing pressure fluctuations within the hydraulic cylinder. Pressure reduction is achieved by increasing the flow channel area and changing the fluid velocity. Depending on actual needs, the fluid velocity and flow channels can be adjusted by changing the number and size of the flow channels in the pressure reducing rod 4, thus generating a reasonable pressure difference to ensure that the pressure inside the piston rod 3 is reduced to a reasonable range.

[0071] In order to ensure that pressure is established when liquid enters the bottom valve 24 and to prevent cross-contamination of high-pressure liquid when it passes through the liquid passage, a dynamic seal 93 is provided on the inner wall where the pressure reducing rod guide sleeve assembly 9 connects with the pressure reducing rod 4, so as to ensure the smooth completion of the lifting column operation.

[0072] The working process of the double telescopic column shown in this embodiment is briefly described below:

[0073] The process of raising the column:

[0074] High-pressure liquid enters the lower chamber 11 of the large cylinder through the lower chamber inlet 13, pushing the middle cylinder 2 to extend upwards;

[0075] After the middle cylinder 2 reaches the set stroke, the bottom valve 24 opens, and the high-pressure liquid enters the lower chamber 22 of the middle cylinder. At the same time, some of the high-pressure liquid enters the pressure-bearing chamber 37 through the deep hole on the pressure-reducing rod 4, together pushing the piston 3 upward until the designed stroke is reached, completing the lifting action.

[0076] The process of column reduction:

[0077] High-pressure liquid enters the upper chamber 12 of the large cylinder through the first upper chamber inlet 14, and simultaneously enters the upper chamber 23 of the middle cylinder and the lower chamber 36 of the piston through the second upper chamber inlet 32, the first deep hole 33, and the first through hole 35 on the piston 3. The dual-channel liquid inlet drives the middle cylinder 2 and the piston 3 to retract synchronously. During the retraction process, the bottom valve 24 opens, and the high-pressure liquid in the pressure chamber 37 enters the lower chamber 22 of the middle cylinder through the second and third deep holes. Together with some of the original high-pressure liquid in the lower chamber 22, it flows back to the external hydraulic system through the lower chamber inlet 13. Similarly, the first upper chamber inlet 14 and the second upper chamber inlet 32 ​​can also be supplied with liquid separately in stages to achieve staged retraction. The specific operation can be freely adjusted according to actual needs.

[0078] The dual telescopic column shown in this embodiment achieves a comprehensive improvement in the performance of the high-pressure hydraulic system through the coordinated design of the deep hole in the piston and the pressure-reducing rod. The second upper chamber inlet 32, the first deep hole 33, and the first through hole 35 inside the piston 3 form an independent inlet channel, significantly shortening the liquid transmission path and optimizing the pressure distribution. Meanwhile, the axial and radial deep holes of the pressure-reducing rod 4 construct an efficient pressure-reducing flow channel, diverting the pressure in the lower chamber 22 of the middle cylinder to the pressure-bearing chamber 37, thus significantly reducing the working pressure of the secondary cylinder. The addition of deep hole pressure relief channels inside the piston 3 and the pressure-reducing rod 4, this dual-channel design not only optimizes the liquid transmission path and ensures the dispersion of the liquid inlet path, transforming local concentrated pressure into a more balanced pressure distribution, reducing peak pressure, and achieving gradual pressure reduction, but also effectively alleviates hydraulic shock by utilizing the gradual pressure reduction characteristics of the deep hole structure. This solves the jamming problem during the traditional column lowering and extends the life of the seals and cylinder by distributing the load. This structure, within a limited structural space, allows for compatibility with existing double telescopic columns without increasing the cylinder diameter or altering the main support structure. It enables upgrades and modifications to traditional double telescopic columns, improving their pressure-bearing capacity, economy, and practicality. It is particularly suitable for high-pressure, high-frequency operating conditions such as in mining machinery, ensuring smooth operation while achieving safety redundancy and adaptive adjustment capabilities.

[0079] In the description of this invention, 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 invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0080] 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 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. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0081] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first and second features are in direct contact, or that they are in indirect contact through an intermediate medium. Furthermore, "above," "over," or "on top" 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," or "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.

[0082] 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.

[0083] 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 double telescopic column of a hydraulic support, comprising a large cylinder (1), a middle cylinder (2), and a piston (3) slidably sleeved axially from the outside in, characterized in that: The middle cylinder (2) has a piston (21) on its outer peripheral wall near the bottom, which is sealed against the inner wall of the large cylinder (1). The piston (21) divides the inner cavity of the large cylinder (1) into a lower chamber (11) and an upper chamber (12). The piston (3) has a piston piston (31) on its outer peripheral wall near the bottom position, which seals against the inner wall of the middle cylinder (2). The piston piston (31) divides the inner cavity of the middle cylinder (2) into the lower middle cylinder cavity (22) and the upper middle cylinder cavity (23). The lower part of the large cylinder (1) is provided with a lower cavity inlet (13) connected to the lower cavity (11) of the large cylinder, and the upper part is provided with a first upper cavity inlet (14) connected to the upper cavity (12) of the large cylinder. The bottom of the middle cylinder (2) is provided with a bottom valve (24) that can selectively connect the lower chamber of the large cylinder (11) and the lower chamber of the middle cylinder (22). The piston rod (3) has a second upper cavity inlet (32) on its head, and the piston rod (3) has a first deep hole (33) that is axially arranged and connected to the second upper cavity inlet (32), and the first deep hole (33) is connected to the upper cavity (23) of the middle cylinder.

2. The double telescopic column of the hydraulic support as described in claim 1, characterized in that: The piston rod (3) has two interconnected second upper chamber inlets (32) on its head. A safety valve (34) is provided at the position of either of the second upper chamber inlets (32), and the other second upper chamber inlet (32) is used to connect to an external hydraulic system.

3. The double telescopic column of the hydraulic support as described in claim 1, characterized in that: The piston rod (3) is provided with a first through hole (35) that extends radially and communicates with the first deep hole (33) near the piston rod piston (31). The first through hole (35) connects the upper cavity (23) of the middle cylinder with the inner cavity of the piston (3).

4. The double telescopic column of the hydraulic support as described in claim 3, characterized in that: The first deep hole (33) and the first through hole (35) are each provided in two at intervals around the axis of the piston (3), and each first deep hole (33) and the first through hole (35) are provided in a one-to-one correspondence.

5. The double telescopic column of the hydraulic support as described in any one of claims 1-4, characterized in that: It also includes a pressure reducing rod (4), which is slidably inserted into the inner cavity of the piston (3) along the axial direction. Its bottom end is fixedly connected to the bottom of the cylinder of the middle cylinder (2), and its top end is provided with a piston part (41) that seals against the inner cavity of the piston (3). The piston part (41) divides the inner cavity of the piston (3) into a lower piston cavity (36) and a pressure bearing cavity (37). The pressure reducing rod (4) is provided with a second deep hole (42) extending axially and a third deep hole (43) extending radially. The second deep hole (42) and the third deep hole (43) are interconnected, and the third deep hole (43) is located near the bottom of the cylinder in the lower cavity (22) of the middle cylinder. The second deep hole (42) is connected to the pressure-bearing cavity (37), and the third deep hole (43) is connected to the lower cavity (22) of the middle cylinder.

6. The double telescopic column of the hydraulic support as described in claim 5, characterized in that: The pressure reducing rod (4) is simultaneously fixed to the bottom of the cylinder body (2) by connecting plug (5) and anti-loosening screw (6); At the center of the bottom of the cylinder block (2), there is a first mounting hole that is compatible with the connecting screw plug (5). The connecting screw plug (5) passes through the first mounting hole and is screwed onto the end of the pressure reducing rod (4). The connecting plug (5) is provided with a second mounting hole that is compatible with the anti-loosening screw (6), and the anti-loosening screw (6) passes through the second mounting hole and is screwed onto the end of the pressure reducing rod (4).

7. The double telescopic column of the hydraulic support as described in claim 6, characterized in that: The connecting plug (5) is provided with a second through hole (51) extending axially and a third through hole (52) extending radially, and the second through hole (51) and the third through hole (52) are interconnected. The second through hole (51) is connected to the second deep hole (42), and the third through hole (52) is connected to the third deep hole (43).

8. The double telescopic column of the hydraulic support as described in claim 7, characterized in that: The second deep hole (42), the third deep hole (43), the second through hole (51), and the third through hole (52) are all provided in two at intervals around the axis of the pressure reducing rod (4), and each of the second deep hole (42), the third deep hole (43), the second through hole (51), and the third through hole (52) is provided in a one-to-one correspondence.

9. The double telescopic column of the hydraulic support as described in claim 5, characterized in that: The upper cavity of the large cylinder (1) is provided with a middle cylinder guide sleeve assembly (7), the upper cavity of the middle cylinder (2) is provided with a piston guide sleeve assembly (8), and the lower cavity of the piston (3) is provided with a pressure reducing rod guide sleeve assembly (9).

10. The double telescopic column of the hydraulic support as described in claim 1, characterized in that: At least two bottom valves (24) are provided at circumferential intervals at the bottom of the cylinder block (2).

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