A multi-stage hydraulic cylinder structure with mechanical and hydraulic double locking

Abstract

The present invention discloses a multi-stage hydraulic cylinder structure with mechanical and hydraulic dual locking, belonging to the field of hydraulic cylinder technology. The structure specifically includes a multi-stage guide rod assembly, comprising a primary guide rod assembly, a secondary guide rod assembly, and a tertiary guide rod assembly. The primary guide rod assembly comprises a first guide rod and a first locking assembly, the secondary guide rod assembly comprises a second guide rod and a second locking assembly, and the tertiary guide rod assembly comprises a third guide rod and a third locking assembly. The present invention utilizes the multi-stage guide rod assembly to improve the stability of the hydraulic piston during its raising and lowering, thereby improving the overall stability of the hydraulic cylinder. Furthermore, when the hydraulic piston reaches its maximum elevation or lowering limit, the hydraulic-mechanical lock assembly in the multi-stage locking assembly can lock the hydraulic piston, enabling it to be quickly positioned, further increasing the overall stability of the hydraulic cylinder and achieving better performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydraulic cylinders, and in particular relates to a multi-stage hydraulic cylinder structure with mechanical and hydraulic double locking. Background Art

[0002] A hydraulic cylinder is a hydraulic actuator that converts hydraulic energy into mechanical energy, performing linear reciprocating motion. It features a simple structure and reliable operation. Using it to achieve reciprocating motion eliminates the need for a reduction gear, eliminates transmission backlash, and provides smooth motion. Therefore, it is widely used in the hydraulic systems of various machines. Hydraulic cylinders can be categorized as single-stage or multi-stage.

[0003] However, when the existing multi-stage extension hydraulic cylinder is in use, the hydraulic piston inside the hydraulic cylinder has poor stability, resulting in poor stability of the hydraulic cylinder as a whole. When hydraulically lifting some objects with strict stability requirements, the existing multi-stage extension hydraulic cylinder is difficult to meet the high stability requirements of such objects, resulting in certain usage limitations of the existing multi-stage extension hydraulic cylinder. Summary of the Invention

[0004] The object of the present invention is to provide a mechanical-hydraulic dual-locking multi-stage hydraulic cylinder structure to solve the problem of poor stability of the hydraulic piston inside the hydraulic cylinder when the existing multi-stage extension hydraulic cylinder is in use as mentioned in the background art.

[0005] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0006] The present invention provides a mechanical-hydraulic double-locking multi-stage hydraulic cylinder structure, comprising a hydraulic extension rod and a multi-stage cylinder assembly, wherein the multi-stage cylinder assembly comprises a fixed cylinder, wherein a first-stage cylinder extending to the outside of the fixed cylinder is provided inside the fixed cylinder, a second-stage cylinder extending to the outside of the first-stage cylinder is provided inside the first-stage cylinder, a hydraulic extension rod extending to the outside of the second-stage cylinder is provided inside the second-stage cylinder, a first-stage cylinder piston connected to the bottom of the first-stage cylinder is provided inside the fixed cylinder, a second-stage cylinder piston connected to the bottom of the second-stage cylinder is provided inside the first-stage cylinder, a third-stage hydraulic piston connected to the bottom of the hydraulic extension rod is provided inside the second-stage cylinder, and a multi-stage guide rod assembly is further provided, wherein the multi-stage guide rod assembly comprises:

[0007] A first-stage guide rod assembly specifically comprises: a first guide rod and a first locking assembly for enabling the first-stage cylinder piston to be locked at the upper and lower ends of the first guide rod, wherein the first locking assembly comprises first bayonet holes provided at the upper and lower ends of the side of the first guide rod and a first hydraulic-mechanical lock assembly for locking or unlocking the first bayonet holes, the first hydraulic-mechanical lock assembly comprising a first mounting bolt mounted on the first-stage cylinder piston, a first sleeve being fixed to the first mounting bolt, a first hydraulic piston being provided on the first sleeve and being capable of sliding within the first sleeve, the first hydraulic piston being connected to the first sleeve via a first spring, and a first sealing rubber ring being provided on the first hydraulic piston;

[0008] A secondary guide rod assembly, specifically comprising: a second guide rod and a second locking assembly for enabling the secondary cylinder piston to be locked at the upper and lower ends of the second guide rod, wherein the second locking assembly includes second bayonet holes provided at the upper and lower ends of the side of the second guide rod and a second hydraulic-mechanical lock assembly for locking or unlocking the second bayonet holes, the second hydraulic-mechanical lock assembly including a second mounting bolt mounted on the secondary cylinder piston, and a second sleeve fixed on the second mounting bolt, a second hydraulic piston capable of sliding within the second sleeve provided on the second sleeve, the second hydraulic piston and the second sleeve being connected by a second spring, and a second sealing rubber ring provided on the first hydraulic piston;

[0009] The three-stage guide rod assembly specifically includes: a third guide rod and a third locking assembly for enabling the three-stage hydraulic piston to be locked at the upper and lower ends of the third guide rod, wherein the third locking assembly includes third bayonet holes provided at the upper and lower ends of the side of the third guide rod and a third hydraulic-mechanical lock assembly for locking or unlocking the third bayonet holes, the third hydraulic-mechanical lock assembly includes a third mounting bolt mounted on the three-stage hydraulic piston, and a third sleeve fixed on the third mounting bolt, a third hydraulic piston capable of sliding within the third sleeve provided on the third sleeve, the third hydraulic piston and the third sleeve being connected by a third spring, and a third sealing rubber ring provided on the first hydraulic piston;

[0010] The set elastic force of the third spring is greater than the set elastic force of the second spring, and the set elastic force of the second spring is greater than the set elastic force of the first spring.

[0011] Preferably, the first-stage cylinder piston divides the interior of the fixed cylinder body into a first-stage cylinder piston lower chamber and a first-stage cylinder piston upper chamber; the second-stage cylinder piston divides the interior of the fixed cylinder body into a second-stage cylinder piston lower chamber and a second-stage cylinder piston upper chamber; the third-stage hydraulic piston divides the interior of the fixed cylinder body into a third-stage hydraulic piston lower chamber and a third-stage hydraulic piston upper chamber.

[0012] Preferably, the first-stage cylinder piston lower chamber, the second-stage cylinder piston lower chamber and the third-stage hydraulic piston lower chamber are connected through a first oil passage assembly; the first-stage cylinder piston upper chamber, the second-stage cylinder piston upper chamber and the third-stage hydraulic piston upper chamber are connected through a second oil passage assembly.

[0013] Preferably, the first oil channel assembly includes a first oil guide channel arranged inside the first-stage cylinder piston and a second oil guide channel arranged inside the second-stage cylinder piston, and also includes a first branch channel and a second branch channel arranged in the wall of the fixed cylinder body and a third branch channel and a fourth branch channel arranged in the wall of the first-stage cylinder body. A first filler nozzle oil channel communicating with the lower chamber of the first-stage cylinder piston and a second filler nozzle oil channel communicating with the upper chamber of the first-stage cylinder piston are provided on the outer wall of the fixed cylinder body. The first branch channel is used to connect the first filler nozzle oil channel and the first oil guide channel, and the third branch channel is used to connect the first oil guide channel and the second oil guide channel.

[0014] Preferably, the second oil channel assembly includes a third oil guide channel provided in the wall of the first cylinder body and a fourth oil guide channel provided in the wall of the second cylinder body, the third oil guide channel is used to connect the upper chamber of the first cylinder piston and the upper chamber of the second cylinder piston, and the fourth oil guide channel is used to connect the upper chamber of the second cylinder piston and the upper chamber of the third hydraulic piston.

[0015] Preferably, a first sealing ring is provided at the connection between the fixed cylinder body and the first-stage cylinder body, a second sealing ring is provided on the outside of the first-stage cylinder piston, a third sealing ring is provided at the connection between the first-stage cylinder body and the second-stage cylinder body, a fourth sealing ring is provided on the outside of the second-stage cylinder piston, a fifth sealing ring is provided at the connection between the second-stage cylinder body and the hydraulic extension rod, and a sixth sealing ring is provided on the outside of the third-stage hydraulic piston.

[0016] Preferably, a first limiting boss and a second limiting boss for limiting the first-stage cylinder piston are provided on the inner wall of the fixed cylinder body, a third limiting boss and a fourth limiting boss for limiting the second-stage cylinder piston are provided on the inner wall of the first-stage cylinder body, and a fifth limiting boss and a sixth limiting boss for limiting the third-stage hydraulic piston are provided inside the second-stage cylinder body. A first connecting thread is provided on the fixed cylinder body, a second connecting thread is provided on the first-stage cylinder body, and a third connecting thread is provided on the second-stage cylinder body. The top of the hydraulic extension rod is connected to a rotary joint through threaded rotation.

[0017] Preferably, the first-level guide rod assembly also includes a first locking nut provided on the first-level cylinder piston, and a first copper gasket is provided at the bottom of the first locking nut, a first oil channel and a second oil channel are provided on the first guide rod, and a first sealing rubber ring is provided on the top of the first locking nut; the second-level guide rod assembly also includes a second locking nut provided on the second-level cylinder piston, and a second copper gasket is provided at the bottom of the second locking nut, a third oil channel and a fourth oil channel are provided on the top of the second guide rod, and a second sealing rubber ring is provided on the top of the second locking nut; the third-level guide rod assembly also includes a third locking nut provided on the third-level hydraulic piston, and a third copper gasket is provided at the bottom of the third locking nut, a fifth oil channel and a sixth oil channel are provided on the top of the third guide rod, and a third sealing rubber ring is provided on the top of the third locking nut.

[0018] Preferably, both the first take-over nozzle oil passage and the second take-over nozzle oil passage are provided with a flow limiting nozzle, one end of the flow limiting nozzle is provided with a mounting baffle which is installed in cooperation with the first take-over nozzle oil passage or the second take-over nozzle oil passage, the flow limiting nozzle is also provided with a first oil port, an opening and closing valve flap shaft is provided inside the flow limiting nozzle, and an opening and closing valve flap is provided on the opening and closing valve flap shaft, the flow limiting nozzle is also provided with a second oil port which cooperates with the opening and closing valve flap, and a limiting ring is provided on the outer side of one end of the flow limiting nozzle for limiting the opening and closing valve flap.

[0019] Compared with the existing technology, one or more of the above technical solutions have the following beneficial effects:

[0020] The multi-stage guide rod assembly can improve the stability of the hydraulic piston when the hydraulic piston is raised or lowered, thereby improving the overall stability of the hydraulic cylinder. When the hydraulic piston rises or falls to the maximum limit, the multi-stage hydraulic mechanical lock assembly can lock the hydraulic piston so that it can be quickly positioned, further increasing the overall stability of the hydraulic cylinder and achieving better use effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0022] Figure 1 It is a schematic diagram of the main structure of one embodiment of the present invention;

[0023] Figure 2 This is a schematic diagram of the structure of one state of the first-stage cylinder piston of the present invention;

[0024] Figure 3 This is a schematic diagram of the structure of one state of the secondary cylinder piston of the present invention;

[0025] Figure 4This is a schematic diagram of the structure of one state of the three-stage oil piston of the present invention;

[0026] Figure 5 It is a schematic structural diagram of the first hydraulic mechanical lock assembly of the present invention;

[0027] Figure 6 This is a schematic diagram of the state structure of the first hydraulic mechanical lock assembly of the present invention;

[0028] Figure 7 Schematic diagram of the structure of the flow limiting nozzle of the present invention;

[0029] Figure 8 It is a schematic diagram of the main structure of the first guide assembly of the present invention;

[0030] Figure 9 It is a schematic diagram of the main structure of another embodiment of the present invention;

[0031] Figure 10 is a structural schematic diagram of a multi-stage guide rod assembly in another embodiment of the present invention;

[0032] In the picture:

[0033] 1-1, fixed cylinder body; 1-2, first nozzle oil passage; 1-3, first branch pipe passage; 1-4, second branch pipe passage; 1-5, second nozzle oil passage; 1-6, first sealing ring; 1-7, first limiting boss; 1-8, second limiting boss; 1-9, first connecting thread; 1-10, sealing element;

[0034] 2-1, first-stage cylinder body; 2-2, first-stage cylinder piston; 2-3, first oil guide channel; 2-4, third branch pipe channel; 2-5, fourth branch pipe channel; 2-6, third oil guide channel; 2-7, second sealing ring; 2-8, third sealing ring; 2-9, third limiting boss; 2-10, fourth limiting boss; 2-11, second connecting thread;

[0035] 3-1, secondary cylinder body; 3-2, secondary cylinder piston; 3-3, second oil guide channel; 3-4, fourth oil guide channel; 3-5, fourth sealing ring; 3-6, fifth sealing ring; 3-7, fifth limiting boss; 3-8, sixth limiting boss; 3-9, third connecting thread;

[0036] 4-1, hydraulic extension rod; 4-2, three-stage hydraulic piston; 4-3, sixth sealing ring; 4-4, rotary joint;

[0037] 5. Primary guide rod assembly; 5-1. First guide rod; 5-2. First locking nut; 5-3. First copper washer; 5-4. First sealing rubber ring; 5-5. First bayonet; 5-6. First oil channel; 5-7. Second oil channel;

[0038] 6. Secondary guide rod assembly; 6-1. Second guide rod; 6-2. Second locking nut; 6-3. Second copper washer; 6-4. Second sealing rubber ring; 6-5. Second bayonet; 6-6. Third oil channel; 6-7. Fourth oil channel;

[0039] 7. Three-stage guide rod assembly; 7-1. Third guide rod; 7-2. Third locking nut; 7-3. Third copper washer; 7-4. Third sealing rubber ring; 7-5. Third bayonet; 7-6. Fifth oil channel; 7-7. Sixth oil channel;

[0040] 8. First hydraulic mechanical lock assembly; 8-1. First hydraulic piston; 8-2. First sealing rubber ring; 8-3. First spring; 8-4. First sleeve; 8-5. First mounting bolt;

[0041] 9. Second hydraulic mechanical lock assembly; 9-1. Second hydraulic piston; 9-2. Second sealing rubber ring; 9-3. Second spring; 9-4. Second sleeve; 9-5. Second mounting bolt;

[0042] 10. Third hydraulic mechanical lock assembly; 10-1. Third hydraulic piston; 10-2. Third sealing rubber ring; 10-3. Third spring; 10-4. Third sleeve; 10-5. Third mounting bolt;

[0043] 11. Flow restrictor; 11-1. Mounting baffle; 11-2. First oil port; 11-3. Open / close valve disc shaft; 11-4. Open / close valve disc; 11-5. Second oil port; 11-6. Limiting ring;

[0044] A1, lower chamber of the first-stage cylinder piston; A2, upper chamber of the first-stage cylinder piston; B1, lower chamber of the second-stage cylinder piston; B2, upper chamber of the second-stage cylinder piston; C1, lower chamber of the third-stage cylinder piston; C2, upper chamber of the third-stage cylinder piston;

[0045] 12. Multi-stage cylinder assembly; 13. Multi-stage guide rod assembly; 14. First oil channel assembly; 15. Second oil channel assembly; 16. First locking assembly; 17. Second locking assembly; 18. Third locking assembly. DETAILED DESCRIPTION

[0046] In order to enable those skilled in the art to better understand the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of this application.

[0047] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present application described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0048] In this application, terms such as "upper," "lower," "left," "right," "front," "back," "top," "bottom," "inner," "outer," "center," "vertical," "horizontal," "transverse," and "longitudinal" indicate positions or locations based on the positions or locations shown in the accompanying drawings. These terms are primarily intended to better describe this application and its embodiments and are not intended to limit the devices, elements, or components indicated to having a specific orientation, or to being constructed or operated in a specific orientation.

[0049] Furthermore, some of the above terms may be used to express other meanings besides indicating a position or location. For example, the term "on" may also be used to indicate a dependency or connection in certain circumstances. Those skilled in the art will understand the specific meanings of these terms in this application based on the specific circumstances.

[0050] Furthermore, the terms "installed," "disposed," "provided with," "connected," "connected," and "socketed" should be interpreted broadly. For example, they can refer to fixed connections, removable connections, or integral structures; mechanical connections or electrical connections; direct connections, indirect connections through an intermediary, or internal communication between two devices, elements, or components. Those skilled in the art will understand the specific meanings of these terms in this application based on the specific circumstances.

[0051] See also Figures 1-10A multi-stage hydraulic cylinder structure with mechanical and hydraulic double locking includes a hydraulic extension rod 4-1 and a multi-stage cylinder assembly 12. The multi-stage cylinder assembly 12 includes at least a fixed cylinder 1-1, a first-stage cylinder 2-1, and a second-stage cylinder 3-1, which are nested in sequence from the outside to the inside. The first-stage cylinder 2-1 slides within the fixed cylinder 1-1 via a first-stage cylinder piston 2-2 fixed at its cylinder bottom, the second-stage cylinder 3-1 slides within the first-stage cylinder 2-1 via a second-stage cylinder piston 3-2 fixed at its cylinder bottom, and the hydraulic extension rod 4-1 slides within the second-stage cylinder 3-1 via a third-stage hydraulic piston 4-2 fixed at its rod bottom. The multi-stage guide rod assembly 13 is also included. The multi-stage guide rod assembly 13 includes:

[0052] The first-stage guide rod assembly 5 specifically includes: a first guide rod 5-1, which is vertically arranged at the bottom end of the fixed cylinder body 1-1 and passes through the first-stage cylinder piston 2-2, so as to enable the first-stage cylinder piston 2-2 to slide only along the vertical direction of the first guide rod 5-1;

[0053] The secondary guide rod assembly 6 specifically includes: a second guide rod 6-1, which is vertically arranged on the primary cylinder piston 2-2 and passes through the secondary cylinder piston 3-2, so as to enable the secondary cylinder piston 3-2 to slide only along the vertical direction of the second guide rod 6-1;

[0054] The three-stage guide rod assembly 7 specifically includes: a third guide rod 7-1, which is vertically arranged on the second-stage cylinder piston 3-2 and passes through the third-stage hydraulic piston 4-2, so as to enable the third-stage hydraulic piston 4-2 to slide only along the vertical direction of the third guide rod 7-1;

[0055] The first-stage cylinder piston 2-2 divides the interior of the fixed cylinder body 1-1 into the first-stage cylinder piston lower chamber A1 and the first-stage cylinder piston upper chamber A2; the second-stage cylinder piston 3-2 divides the interior of the fixed cylinder body 1-1 into the second-stage cylinder piston lower chamber B1 and the second-stage cylinder piston upper chamber B2; the third-stage hydraulic piston 4-2 divides the interior of the fixed cylinder body 1-1 into the third-stage hydraulic piston lower chamber C1 and the third-stage hydraulic piston upper chamber C2;

[0056] The first cylinder piston lower chamber A1, the second cylinder piston lower chamber B1 and the third hydraulic piston lower chamber C1 are connected through the first oil passage assembly 14; the first cylinder piston upper chamber A2, the second cylinder piston upper chamber B2 and the third hydraulic piston upper chamber C2 are connected through the second oil passage assembly 15;

[0057] A first locking assembly 16 is provided on the first guide rod 5-1 for locking or unlocking the first-stage cylinder piston 2-2 at the upper and lower ends of the first guide rod 5-1; a second locking assembly 17 is provided on the second guide rod 6-1 for locking or unlocking the second-stage cylinder piston 3-2 at the upper and lower ends of the second guide rod 6-1; and a third locking assembly 18 is provided on the third guide rod 7-1 for locking or unlocking the third-stage hydraulic piston 4-2 at the upper and lower ends of the third guide rod 7-1.

[0058] The first locking assembly 16 includes a first bayonet 5-5 provided at the upper and lower ends of the side of the first guide rod 5-1 along the length direction of the first guide rod 5-1 and a first hydraulic mechanical lock assembly 8 provided on the first cylinder piston 2-2. The first hydraulic mechanical lock assembly 8 includes a first mounting bolt 8-5 installed on the first cylinder piston 2-2, and a first sleeve 8-4 is fixed on the first mounting bolt 8-5. The first sleeve 8-4 is provided with a first hydraulic piston 8-1 that can slide in the first sleeve 8-4. The first hydraulic piston 8-1 and the first sleeve 8-4 are connected by a first spring 8-3. The first hydraulic piston 8-1 is provided with a first sealing rubber ring 8-2.

[0059] The second locking assembly 17 includes a second bayonet 6-5 provided at the upper and lower ends of the side of the second guide rod 6-1 along the length direction of the second guide rod 6-1 and a second hydraulic mechanical lock assembly 9 provided on the secondary cylinder piston 3-2. The second hydraulic mechanical lock assembly 9 includes a second mounting bolt 9-5 installed on the secondary cylinder piston 3-2, and a second sleeve 9-4 is fixed on the second mounting bolt 9-5. The second sleeve 9-4 is provided with a second hydraulic piston 9-1 that can slide in the second sleeve 9-4. The second hydraulic piston 9-1 and the second sleeve 9-4 are connected by a second spring 9-3. The first hydraulic piston 8-1 is provided with a second sealing rubber ring 9-2.

[0060] The third locking assembly 18 includes a third bayonet 7-5 provided at the upper and lower ends of the side of the third guide rod 7-1 along the length direction of the third guide rod 7-1 and a third hydraulic mechanical lock assembly 10 provided on the third hydraulic piston 4-2. The third hydraulic mechanical lock assembly 10 includes a third mounting bolt 10-5 installed on the third hydraulic piston 4-2, and a third sleeve 10-4 is fixed on the third mounting bolt 10-5. The third sleeve 10-4 is provided with a third hydraulic piston 10-1 that can slide in the third sleeve 10-4. The third hydraulic piston 10-1 and the third sleeve 10-4 are connected by a third spring 10-3, and a third sealing rubber ring 10-2 is provided on the first hydraulic piston 8-1.

[0061] Please refer to Figure 1As shown, the first oil circuit channel assembly 14 includes a first oil guide channel 2-3 arranged inside the first-stage cylinder piston 2-2 and a second oil guide channel 3-3 arranged inside the second-stage cylinder piston 3-2, and also includes a first branch channel 1-3 and a second branch channel 1-4 arranged in the wall of the fixed cylinder body 1-1, and a third branch channel 2-4 and a fourth branch channel 2-5 arranged in the wall of the first-stage cylinder body 2-1. A first take-over nozzle oil channel 1-2 communicating with the lower chamber A1 of the first-stage cylinder piston and a second take-over nozzle oil channel 1-5 communicating with the upper chamber A2 of the first-stage cylinder piston are provided on the outer wall of the fixed cylinder body 1-1. The first branch channel 1-3 is used to connect the first take-over nozzle oil channel 1-2 and the first oil guide channel 2-3, and the third branch channel 2-4 is used to connect the first oil guide channel 2-3 and the second oil guide channel 3-3.

[0062] Please refer to Figure 1 As shown, the second oil channel assembly 15 includes a third oil guide channel 2-6 provided in the wall of the first cylinder body and a fourth oil guide channel 3-4 provided in the wall of the second cylinder body. The third oil guide channel 2-6 is used to connect the upper chamber A2 of the first cylinder piston and the upper chamber B2 of the second cylinder piston. The fourth oil guide channel 3-4 is used to connect the upper chamber B2 of the second cylinder piston and the upper chamber C2 of the third hydraulic piston.

[0063] The first-stage guide rod assembly 5 also includes a first locking nut 5-2 provided on the first-stage cylinder piston 2-2, and a first copper gasket 5-3 is provided at the bottom of the first locking nut 5-2. A first oil passage 5-6 and a second oil passage 5-7 are provided on the first guide rod 5-1, and a first sealing rubber ring 5-4 is provided on the top of the first locking nut 5-2. The second-stage guide rod assembly 6 also includes a second locking nut 6-2 provided on the second-stage cylinder piston 3-2, and a second copper gasket 6-3 is provided at the bottom of the second locking nut 6-2. A third oil passage 6-6 and a fourth oil passage 6-7 are provided on the second guide rod 6-1, and a second sealing rubber ring 6-4 is provided on the top of the second locking nut 6-2. The third-stage guide rod assembly 7 also includes a third locking nut 7-2 provided on the third-stage hydraulic piston 4-2, and a third copper washer 7-3 is provided on the bottom of the third locking nut 7-2. A fifth oil passage 7-6 and a sixth oil passage 7-7 are provided on the third guide rod 7-1, and a third sealing rubber ring 7-4 is provided on the top of the third locking nut 7-2.

[0064] The first-stage guide rod assembly 5, the second-stage guide rod assembly 6 and the third-stage guide rod assembly 7 have the same structure. Figure 8As shown, taking the first-stage guide rod assembly 5 as an example, it consists of a first guide rod 5-1, a first locking nut 5-2, a first copper washer 5-3, a first sealing rubber ring 5-4, a first oil channel 5-6, a second oil channel 5-7, and a first bayonet 5-5. The first guide rod 5-1 prevents the first-stage cylinder piston 2-2 from rotating, ensuring accurate positioning and connection of each oil channel; the first locking nut 5-2 is mounted on the fixed cylinder body 1-1 to secure the first guide rod 5-1; the first copper washer 5-3 strengthens the compression and fixation of the first guide rod 5-1; the first sealing rubber ring 5-4 is used to seal the corresponding components; and the first bayonet 5-5 is used to connect to the first hydraulic piston 8-1.

[0065] The first hydraulic mechanical lock assembly 8, the second hydraulic mechanical lock assembly 9 and the third hydraulic mechanical lock assembly 10 have the same structure. Figure 5 As shown, taking the first hydraulic mechanical lock assembly 8 as an example, it is composed of a first hydraulic piston 8-1, a first sealing rubber ring 8-2, a first spring 8-3, a first sleeve 8-4 and a first mounting bolt 8-5. Among them, the first hydraulic piston 8-1 is used to lock and open between the first cylinder piston 2-2 and the first guide rod 5-1; the first sealing rubber ring 8-2 is used to seal the mechanical lock to prevent hydraulic oil from entering the interior of the mechanical lock; the first spring 8-3 provides a driving force for the first hydraulic piston 8-1 to overcome the oil pressure in the first oil channel 5-6, and ensure that the first hydraulic piston 8-1 extends when the first oil channel 5-6 is at low oil pressure; the first sleeve 8-4 is used to fix the first hydraulic piston 8-1 and the first spring 8-3, and the first hydraulic piston 8-1 can slide in the first sleeve 8-4; unscrewing the first mounting bolt 8-5 is used to install the first hydraulic piston 8-1, the first sealing rubber ring 8-2, the first spring 8-3 and the first sleeve 8-4; screwing on the first mounting bolt 8-5 is to fix and seal the first hydraulic piston 8-1, the first sealing rubber ring 8-2, the first spring 8-3 and the first sleeve 8-4;

[0066] Please refer to Figure 1 As shown, a first sealing ring 1-6 is provided at the connection between the fixed cylinder body 1-1 and the first-stage cylinder body 2-1, a second sealing ring 2-7 is provided on the outside of the first-stage cylinder piston 2-2, a third sealing ring 2-8 is provided at the connection between the first-stage cylinder body 2-1 and the second-stage cylinder body 3-1, a fourth sealing ring 3-5 is provided on the outside of the second-stage cylinder piston 3-2, a fifth sealing ring 3-6 is provided at the connection between the second-stage cylinder body 3-1 and the hydraulic extension rod 4-1, and a sixth sealing ring 4-3 is provided on the outside of the third-stage hydraulic piston 4-2;

[0067] All of the above sealing rings, sealing rubber rings and sealing rubber rings are commercially available. In order to distinguish the sealing rings in the present invention, the sealing rings are divided into first sealing rings, second sealing rings, etc., for the purpose of convenience of distinction only. There is no substantial difference between the sealing rings. In addition, more specifically, the sealing rings in the present invention are specifically arranged at the following locations:

[0068] like Figure 1 As shown, there are two sealing rings at the interface between the fixed cylinder body 1-1 and the first-level cylinder body 2-1, at the interface between the first-level cylinder piston 2-2 and the fixed cylinder body 1-1, at the interface between the first-level cylinder body 2-1 and the second-level cylinder body 3-1, at the interface between the second-level cylinder piston 3-2 and the first-level cylinder body 2-1, at the interface between the second-level cylinder body 3-1 and the hydraulic extension rod 4-1, and at the interface between the third-level hydraulic piston 4-2 and the second-level cylinder body 3-1, for sealing the hydraulic oil in the hydraulic cylinder.

[0069] There are sealing rings at the interface between the first guide rod 5-1 and the first-stage cylinder piston 2-2, at the interface between the second guide rod 6-1 and the second-stage cylinder piston 3-2, and at the interface between the third guide rod 7-1 and the third-stage hydraulic piston 4-2, which are used to seal the hydraulic oil in the hydraulic cylinder.

[0070] There are sealing rings at the first connecting thread 1-9, the second connecting thread 2-11 and the third connecting thread 3-9, which are used to seal the hydraulic oil in the hydraulic cylinder.

[0071] There are sealing rings at the first mounting bolt 8-5, the second mounting bolt 9-5 and the third mounting bolt 10-5, which are used to seal the hydraulic oil in the hydraulic cylinder;

[0072] also, Figure 1 1-10 are seals, which are actually sealing rings;

[0073] Please refer to Figure 1As shown, the inner wall of the fixed cylinder body 1-1 is provided with a first limiting boss 1-7 and a second limiting boss 1-8 for limiting the first-stage cylinder piston 2-2, the inner wall of the first-stage cylinder body 2-1 is provided with a third limiting boss 2-9 and a fourth limiting boss 2-10 for limiting the second-stage cylinder piston 3-2, the interior of the second-stage cylinder body 3-1 is provided with a fifth limiting boss 3-7 and a sixth limiting boss 3-8 for limiting the third-stage hydraulic piston 4-2, and the fixed cylinder body 1-1 is provided with a first limiting boss 1-7 and a second limiting boss 1-8 for limiting the first-stage cylinder piston 2-2. A first connecting thread 1-9 is provided, a second connecting thread 2-11 is provided on the first-stage cylinder body 2-1, and a third connecting thread 3-9 is provided on the second-stage cylinder body 3-1. The top of the hydraulic extension rod 4-1 is connected to a rotary joint 4-4 by a threaded rotation. The rotary joint 4-4 and the hydraulic extension rod 4-1 are connected by a long thread and a certain rotation margin is left, so that the rotary joint 4-4 can rotate freely in the hydraulic extension rod 4-1, which can offset the influence of load torsion on the hydraulic cylinder;

[0074] Specifically, if Figure 1 As shown, to facilitate the description of the working process of the hydraulic cylinder, it is assumed that the cylinder body is filled with hydraulic oil, and the first take-off nozzle oil passage 1-2 and the second take-off nozzle oil passage 1-5 are in a closed state under the action of the external hydraulic valve. At this time, the hydraulic oil in the lower chamber A1 of the first cylinder piston, the lower chamber B1 of the second cylinder piston, and the lower chamber C1 of the tertiary hydraulic piston are all in a low-pressure state, and the hydraulic oil in the upper chamber A2 of the first cylinder piston, the upper chamber B2 of the second cylinder piston, and the upper chamber C2 of the tertiary hydraulic piston are all in a high-pressure state, so that the hydraulic cylinder structure is in a fully retracted and locked state (for the convenience of more concise description, hereinafter referred to as A1 chamber, A2 chamber, B1 chamber, B2 chamber, C1 chamber, and C2 chamber).

[0075] At this time, the first-stage cylinder piston 2-2 is in close contact with the first limiting boss 1-7; the hydraulic oil in the A1 chamber is in a low-pressure state, and the first hydraulic piston 8-1 in the first hydraulic mechanical lock assembly 8 is subjected to the spring force of the first spring 8-3, which is greater than the pressure of the hydraulic oil from the first oil channel 5-6. Under the action of the first spring 8-3, the first hydraulic piston 8-1 extends into the first bayonet 5-5 of the first oil channel 5-6, so that the first-stage cylinder piston 2-2 is locked together with the first guide rod 5-1 and cannot move.

[0076] The secondary cylinder piston 3-2 is in close contact with the third limiting boss 2-9; the hydraulic oil in the B1 chamber is in a low-pressure state, and the second hydraulic piston 9-1 in the second hydraulic mechanical lock assembly 9 is subjected to the spring force of the second spring 9-3, which is greater than the pressure of the hydraulic oil from the third oil channel 6-6. Under the action of the second spring 9-3, the second hydraulic piston 9-1 extends into the second bayonet 6-5 of the third oil channel 6-6, so that the secondary cylinder piston 3-2 is locked together with the second guide rod 6-1 and cannot move.

[0077] The third-stage hydraulic piston 4-2 is tightly attached to the fifth limiting boss 3-7; the hydraulic oil in the C1 chamber is in a low-pressure state, and the third hydraulic piston 10-1 in the third hydraulic mechanical lock assembly 10 is subjected to the spring force of the third spring 10-3, which is greater than the pressure of the hydraulic oil from the fifth oil channel 7-6. Under the action of the third spring 10-3, the third hydraulic piston 10-1 extends into the third bayonet 7-5 of the fifth oil channel 7-6, so that the third-stage hydraulic piston 4-2 is locked together with the third guide rod 7-1 and cannot move.

[0078] Please refer to Figure 2 As shown, the extension process of the first-stage cylinder 2-1 is as follows:

[0079] When high-pressure oil is filled into the first filler nozzle oil passage 1-2, the second filler nozzle oil passage 1-5 is connected to the low-pressure return oil line. High-pressure oil enters chamber A1 through the first filler nozzle oil passage 1-2. Simultaneously, high-pressure oil enters chamber B1 through the first branch pipe passage 1-3 and the first oil guide passage 2-3. Simultaneously, high-pressure oil enters chamber C1 through the third branch pipe passage 2-4 and the second oil guide passage 3-3.

[0080] Fourth oil-conducting passage 3-4 connects chambers C2 and B2, while third oil-conducting passage 2-6 connects chambers B2 and A2. Chamber A2 connects to second filler nozzle oil passage 1-5. Because second filler nozzle oil passage 1-5 is connected to the low-pressure return line, the hydraulic oil in chambers C2, B2, and A2 is all in a low-pressure return state.

[0081] The high-pressure oil entering the A1 chamber passes through the first oil channel 5-6, pushing the first hydraulic piston 8-1 in the first hydraulic mechanical lock assembly 8 to retract into the first-stage cylinder piston 2-2, so that the first-stage cylinder piston 2-2 is unlocked from the first guide rod 5-1; since the A2 chamber is a low-pressure oil area, the pressure on the lower surface of the first-stage cylinder piston 2-2 is greater than the pressure on its upper surface, so the high-pressure oil entering the A1 chamber will push the first-stage cylinder piston 2-2 to move upward.

[0082] The set elastic force of the third spring 10-3 is greater than the set elastic force of the second spring 9-3 and greater than the set elastic force of the first spring 8-3. The set elastic force is adjusted by changing the spring elastic coefficient based on the working oil pressure input and output of the hydraulic cylinder and the pressure generated by the compression of the residual air in the hydraulic mechanical lock.

[0083] When the high-pressure oil pressure in the A1 chamber causes the first hydraulic piston 8-1 to retract and unlock, the high-pressure oil pressure entering the B1 chamber is equal to the high-pressure oil in the A1 chamber, which will generate upward pressure on the secondary cylinder piston 3-2. However, since the set elastic force of the second spring 9-3 is greater than the set elastic force of the first spring 8-3, the second hydraulic piston 9-1 in the second hydraulic mechanical lock assembly 9 will not retract at this time, and the secondary cylinder piston 3-2 continues to be locked together with the second guide rod 6-1.

[0084] Similarly, when the high-pressure oil pressure in the A1 chamber causes the first hydraulic piston 8-1 to retract and unlock, the high-pressure oil pressure entering the C1 chamber is equal to the high-pressure oil in the A1 chamber and the B1 chamber, which will produce upward pressure on the tertiary hydraulic piston 4-2. However, since the set elastic force of the third spring 10-3 is greater than the set elastic force of the second spring 9-3 and the set elastic force of the first spring 8-3, the third hydraulic piston 10-1 in the third hydraulic mechanical lock assembly 10 will not retract at this time, and the tertiary hydraulic piston 4-2 continues to be locked together with the third guide rod 7-1.

[0085] The upward movement of piston 2-2 in the first-stage cylinder squeezes the low-pressure oil in chamber A2 out through oil passage 1-5 of the second take-off nozzle. It also causes the first branch passage 1-3 and first oil guide passage 2-3 to shift, preventing high-pressure oil from entering chambers B1 and C1, and preventing the oil pressure in these chambers from rising. At this point, hydraulic oil is trapped in chambers B1, C1, B2, and C2. This trapped hydraulic oil locks the upper and lower surfaces of piston 3-2 in the second-stage cylinder and piston 4-2 in the third-stage cylinder, facilitating cushioning and stabilization during the hydraulic cylinder's movement.

[0086] This state then persists until the first-stage cylinder piston 2-2 reaches the second stop boss 1-8, where it is blocked and stops extending upward. At this point, the first hydraulic piston 8-1 in the first hydraulic-mechanical lock assembly 8 is aligned with the second oil passage 5-7. Because chamber A2 is a low-pressure return chamber, the spring force exerted on the first spring 8-3 on the first hydraulic piston 8-1 is greater than the hydraulic oil pressure within the second oil passage 5-7. Consequently, the first hydraulic piston 8-1 extends into the first latch 5-5 of the second oil passage 5-7, locking the first-stage cylinder piston 2-2 with the first guide rod 5-1 and preventing the hydraulic cylinder from moving due to accidental hydraulic oil decompression.

[0087] Please refer to Figure 3 As shown, the extension process of the secondary cylinder 3-1 is as follows:

[0088] At the next moment, the extension process of the secondary cylinder 3-1 is similar to the extension process of the primary cylinder 2-1.

[0089] When the first-stage cylinder piston 2-2 moves to the second limiting boss 1-8, the second branch channel 1-4 connects to the first oil-conducting channel 2-3. High-pressure oil continues to support and compress the first-stage cylinder piston 2-2. Simultaneously, the high-pressure oil enters chamber B1 through the second branch channel 1-4 and the first oil-conducting channel 2-3, and then enters chamber C1 through the third branch channel 2-4 and the second oil-conducting channel 3-3.

[0090] As the amount of oil entering the B1 chamber increases, the oil pressure in the B1 chamber begins to rise. The high-pressure oil entering the B1 chamber passes through the third oil channel 6-6, pushing the second hydraulic piston 9-1 in the second hydraulic mechanical lock assembly 9 to retract into the secondary cylinder piston 3-2, so that the secondary cylinder piston 3-2 is unlocked from the second guide rod 6-1; since the B2 chamber is a low-pressure oil area, the pressure on the lower surface of the secondary cylinder piston 3-2 is greater than the pressure on its upper surface, so the high-pressure oil entering the B1 chamber will push the secondary cylinder piston 3-2 to move upward.

[0091] When the high-pressure oil pressure in the B1 chamber causes the second hydraulic piston 9-1 to retract and unlock, the high-pressure oil pressure entering the C1 chamber is equal to the high-pressure oil in the B1 chamber, which will generate upward pressure on the tertiary hydraulic piston 4-2. However, since the set elastic force of the third spring 10-3 is greater than the set elastic force of the second spring 9-3, the third hydraulic piston 10-1 in the third hydraulic mechanical lock assembly 10 will not retract at this time, and the tertiary hydraulic piston 4-2 continues to be locked together with the third guide rod 7-1.

[0092] Secondary cylinder piston 3-2 extends upward, squeezing low-pressure oil from chamber B2 through third oil-conducting passage 2-6 into chamber A2, where it is discharged through second takeover nozzle oil passage 1-5. Furthermore, third branch passage 2-4 and second oil-conducting passage 3-3 are offset, preventing high-pressure oil from entering chamber C1. Both chambers C1 and C2 now contain sealed hydraulic oil, which acts as a lock on the upper and lower surfaces of tertiary hydraulic piston 4-2, facilitating cushioning and stabilization during hydraulic cylinder movement.

[0093] This state then persists until the secondary cylinder piston 3-2 reaches the fourth limiting boss 2-10, where it is stopped by the fourth limiting boss 2-10. At this point, the second hydraulic piston 9-1 in the second hydraulic-mechanical lock assembly 9 is aligned with the fourth oil passage 6-7. Because chamber B2 is a low-pressure return chamber, the spring force exerted on the second hydraulic piston 9-1 by the second spring 9-3 is greater than the hydraulic oil pressure within the fourth oil passage 6-7. Consequently, the second hydraulic piston 9-1 extends into the second latch 6-5 of the fourth oil passage 6-7, locking the secondary cylinder piston 3-2 with the second guide rod 6-1 and preventing any hydraulic cylinder movement caused by accidental hydraulic oil decompression.

[0094] Please refer to Figure 4 , the extension process of the hydraulic extension rod 4-1 is:

[0095] At the next moment, the extension process of the hydraulic extension rod 4-1 is similar to the extension process of the first-stage cylinder 2-1 and the second-stage cylinder 3-1.

[0096] When the second-stage piston 3-2 stops at the fourth limiting boss 2-10, the fourth branch channel 2-5 connects to the second oil-conducting channel 3-3. At this point, high-pressure oil, while maintaining support and compression on the first-stage and second-stage pistons 2-2 and 3-2, enters chamber C1 through the fourth branch channel 2-5 and the second oil-conducting channel 3-3.

[0097] As the amount of oil entering the C1 chamber increases, the oil pressure in the C1 chamber begins to rise. The high-pressure oil entering the C1 chamber pushes the third hydraulic piston 10-1 in the third hydraulic mechanical lock assembly 10 back into the third hydraulic piston 4-2 through the fifth oil passage 7-6, so that the third hydraulic piston 4-2 is unlocked from the third guide rod 7-1. Since the C2 chamber is a low-pressure oil area, the pressure on the lower surface of the third hydraulic piston 4-2 is greater than the pressure on its upper surface. Therefore, the high-pressure oil entering the C1 chamber will push the third hydraulic piston 4-2 to move upward, driving the hydraulic extension rod 4-1 to extend, and at the same time squeeze the low-pressure oil in the C2 chamber into the B2 chamber through the fourth oil guide passage 3-4, and then into the A2 chamber through the third oil guide passage 2-6, and discharged through the second takeover nozzle oil passage 1-5.

[0098] This state then persists until the tertiary hydraulic piston 4-2 reaches the sixth stop boss 3-8, where it is blocked and stops extending upward. At this point, the third hydraulic piston 10-1 in the third hydraulic-mechanical lock assembly 10 is aligned with the sixth oil passage 7-7. Because chamber C2 is a low-pressure return chamber, the spring force exerted by the third spring 10-3 on the third hydraulic piston 10-1 is greater than the hydraulic oil pressure within the sixth oil passage 7-7. Consequently, the third hydraulic piston 10-1 extends into the third latch 7-5 of the sixth oil passage 7-7, locking the tertiary hydraulic piston 4-2 with the third guide rod 7-1 and preventing hydraulic cylinder movement due to accidental hydraulic oil decompression.

[0099] From then on, the hydraulic cylinder extension process is completed, all cylinder body components are supported and compressed by high-pressure oil, and are locked by the first hydraulic mechanical lock component 8, the second hydraulic mechanical lock component 9 and the third hydraulic mechanical lock component 10.

[0100] Please refer to Figure 4 As shown, the hydraulic cylinder is in the fully extended position.

[0101] The hydraulic cylinder retraction process is as follows:

[0102] (1) The retraction process of the first-stage cylinder 2-1 is as follows:

[0103] The first take-over nozzle oil passage 1-2 is connected to the low-pressure oil return pipeline, and the second take-over nozzle oil passage 1-5 is filled with high-pressure oil.

[0104] After the high-pressure oil enters the A2 chamber, it applies downward pressure to the upper surface of the first-stage cylinder piston 2-2; at the same time, the high-pressure oil enters the B2 chamber through the third oil guide channel 2-6, applying downward pressure to the upper surface of the second-stage cylinder piston 3-2; at the same time, the high-pressure oil enters the C2 chamber through the fourth oil guide channel 3-4, applying downward pressure to the upper surface of the third-stage hydraulic piston 4-2.

[0105] The high-pressure oil entering the A2 chamber passes through the second oil passage 5-7, pushing the first hydraulic piston 8-1 in the first hydraulic mechanical lock assembly 8 to retract into the first-stage cylinder piston 2-2, so that the first-stage cylinder piston 2-2 is unlocked from the first guide rod 5-1; since the A1 chamber is a low-pressure oil area, the pressure on the upper surface of the first-stage cylinder piston 2-2 is greater than the pressure on its lower surface, so the high-pressure oil entering the A2 chamber will push the first-stage cylinder piston 2-2 to move downward.

[0106] When the high-pressure oil pressure in the A2 chamber causes the first hydraulic piston 8-1 to retract and unlock, the high-pressure oil pressure entering the B2 chamber is equal to the high-pressure oil in the A2 chamber, which will produce downward pressure on the secondary cylinder piston 3-2. However, since the set elastic force of the second spring 9-3 is greater than the set elastic force of the first spring 8-3, the second hydraulic piston 9-1 in the second hydraulic mechanical lock assembly 9 will not retract at this time, and the secondary cylinder piston 3-2 continues to be locked together with the second guide rod 6-1.

[0107] Similarly, when the high-pressure oil pressure in the A1 chamber causes the first hydraulic piston 8-1 to retract and unlock, the high-pressure oil pressure entering the C2 chamber is equal to the high-pressure oil in the A2 chamber and the B2 chamber, which will produce downward pressure on the tertiary hydraulic piston 4-2. However, since the set elastic force of the third spring 10-3 is greater than the set elastic force of the second spring 9-3 and the set elastic force of the first spring 8-3, the third hydraulic piston 10-1 in the third hydraulic mechanical lock assembly 10 will not retract at this time, and the tertiary hydraulic piston 4-2 continues to be locked together with the third guide rod 7-1.

[0108] The piston 2-2 of the first-stage cylinder moves downward. On the one hand, it squeezes the low-pressure oil in the A1 chamber and discharges it through the first nozzle oil passage 1-2; on the other hand, it causes the second branch pipe passage 1-4 and the first oil guide passage 2-3 to be staggered. The oil will not be able to enter the A1 chamber from the B1 chamber, and the oil in the C1 chamber will no longer enter the B1 chamber. At this time, the B1 chamber, the C1 chamber, the B2 chamber, and the C2 chamber all have sealed hydraulic oil. These sealed hydraulic oils form a locking effect on the upper and lower surfaces of the second-stage cylinder piston 3-2 and the third-stage hydraulic piston 4-2, which is beneficial to the buffering and stability of the hydraulic cylinder structure during movement.

[0109] This state will continue to maintain, with only the first-stage cylinder piston 2-2 moving downward, driving the first-stage cylinder body 2-1, the second-stage cylinder body 3-1 and the hydraulic extension rod 4-1 to move downward at the same time, until the first-stage cylinder piston 2-2 moves downward to the first limit boss 1-7 and stops moving.

[0110] At this point, the first hydraulic piston 8-1 in the first hydraulic-mechanical lock assembly 8 is aligned with the first oil passage 5-6. Because chamber A1 is a low-pressure return chamber, the spring force exerted on the first hydraulic piston 8-1 by the first spring 8-3 is greater than the hydraulic oil pressure within the first oil passage 5-6. Consequently, the first hydraulic piston 8-1 extends into the first latch 5-5 of the first oil passage 5-6, locking the first-stage cylinder piston 2-2 with the first guide rod 5-1 and preventing the hydraulic cylinder from moving due to accidental hydraulic oil pressure release.

[0111] (2) The retraction process of the secondary cylinder 3-1 is as follows:

[0112] When the first-stage cylinder piston 2-2 moves downward to the first limiting boss 1-7 and stops, the first oil guide channel 2-3 is connected to the first branch pipe channel 1-3 and the first nozzle oil channel 1-2, and the B1 chamber is connected to the low-pressure oil return circuit;

[0113] As the amount of oil entering the B2 chamber increases, the oil pressure in the B2 chamber begins to rise. The high-pressure oil entering the B2 chamber passes through the fourth oil channel 6-7, pushing the second hydraulic piston 9-1 in the second hydraulic mechanical lock assembly 9 to retract into the secondary cylinder piston 3-2, so that the secondary cylinder piston 3-2 is unlocked from the second guide rod 6-1; since the B1 chamber is a low-pressure oil area, the pressure on the upper surface of the secondary cylinder piston 3-2 is greater than the pressure on its lower surface, so the high-pressure oil entering the B2 chamber will push the secondary cylinder piston 3-2 to move downward.

[0114] When the high-pressure oil pressure in the B2 chamber causes the second hydraulic piston 9-1 to retract and unlock, the high-pressure oil pressure entering the C2 chamber is equal to the high-pressure oil in the B2 chamber, which will produce downward pressure on the tertiary hydraulic piston 4-2. However, since the set elastic force of the third spring 10-3 is greater than the set elastic force of the second spring 9-3, the third hydraulic piston 10-1 in the third hydraulic mechanical lock assembly 10 will not retract at this time, and the tertiary hydraulic piston 4-2 continues to be locked together with the third guide rod 7-1.

[0115] Secondary cylinder piston 3-2 extends downward, squeezing low-pressure oil from chamber B1 through first oil guide channel 2-3 and first branch channel 1-3, and then out through second filler nozzle oil channel 1-5. Furthermore, the fourth branch channel 2-5 and second oil guide channel 3-3 are offset, preventing high-pressure oil from entering chamber B1 from chamber C1. Both chambers C1 and C2 now contain trapped hydraulic oil, which acts as a lock on the upper and lower surfaces of tertiary hydraulic piston 4-2, facilitating cushioning and stabilization during hydraulic cylinder movement.

[0116] Subsequently, this state persists, with the secondary cylinder piston 3-2 moving downward under the influence of the high-pressure oil in chamber B2 on the upper surface, driving the secondary cylinder body 3-1 and the hydraulic extension rod 4-1 downward simultaneously until the secondary cylinder piston 3-2 reaches the third stop boss 2-9, where it is stopped by the third stop boss 2-9. At this point, the second hydraulic piston 9-1 in the second hydraulic mechanical lock assembly 9 is aligned with the third oil passage 6-6. Because chamber B1 is a low-pressure return chamber, the spring force exerted on the second hydraulic piston 9-1 by the second spring 9-3 is greater than the hydraulic oil pressure in the third oil passage 6-6. Consequently, the second hydraulic piston 9-1 extends into the second latch 6-5 of the third oil passage 6-6, locking the secondary cylinder piston 3-2 with the second guide rod 6-1 and preventing any hydraulic cylinder movement caused by accidental hydraulic oil decompression.

[0117] (3) The retraction process of the hydraulic extension rod is as follows:

[0118] When the secondary cylinder piston 3-2 moves downward to the third limiting boss 2-9 and stops moving, the second oil guide channel 3-3 is connected to the third branch channel 2-4; the first oil guide channel 2-3, the first branch channel 1-3, and the first nozzle oil channel 1-2 are connected, and the C1 chamber is connected to the low-pressure oil return circuit.

[0119] As the amount of oil entering the C2 chamber increases, the oil pressure in the C2 chamber begins to rise. The high-pressure oil entering the C2 chamber passes through the sixth oil passage 7-7, pushing the third hydraulic piston 10-1 in the third hydraulic mechanical lock assembly 10 to retract into the third hydraulic piston 4-2, so that the third hydraulic piston 4-2 is unlocked from the third guide rod 7-1. Since the C1 chamber is a low-pressure oil area, the pressure on the upper surface of the third hydraulic piston 4-2 is greater than the pressure on its lower surface. The third hydraulic piston 4-2 begins to move downward under the action of the high-pressure oil in the C2 chamber on the upper surface, and drives the hydraulic extension rod 4-1 to move downward until the third hydraulic piston 4-2 stops moving when it moves to the fifth limit boss 3-7.

[0120] At this point, the third hydraulic piston 10-1 in the third hydraulic-mechanical lock assembly 10 is aligned with the fifth oil passage 7-6. Because chamber C1 is a low-pressure return chamber, the spring force exerted on the third hydraulic piston 10-1 by the third spring 10-3 is greater than the hydraulic oil pressure within the fifth oil passage 7-6. Consequently, the third hydraulic piston 10-1 extends into the third latch 7-5 of the fifth oil passage 7-6, locking the tertiary hydraulic piston 4-2 with the third guide rod 7-1, preventing hydraulic cylinder movement caused by accidental hydraulic oil pressure release.

[0121] At this point, the entire process of hydraulic cylinder retraction is completed.

[0122] It should be noted that the three-stage extension assembly of the hydraulic cylinder can stay in any initial position without affecting the extension and retraction of the hydraulic cylinder structure.

[0123] In addition, please refer to Figure 9 and Figure 10 Furthermore, in order to facilitate production and manufacturing, the first guide rod 5-1, the second guide rod 6-1 and the third guide rod 7-1 can be integrated into one guide rod, so that the guide rod assembly can effectively save space when used in the hydraulic cylinder. The specific principle is the same as above and will not be repeated here.

[0124] Please refer to Figure 1 and Figure 7 As shown, a flow limiting nozzle 11 is provided on both the first take-over nozzle oil passage 1-2 and the second take-over nozzle oil passage 1-5, and a mounting baffle 11-1 is provided at one end of the flow limiting nozzle 11 for cooperating with the first take-over nozzle oil passage 1-2 or the second take-over nozzle oil passage 1-5. A first oil port 11-2 is also provided on the flow limiting nozzle 11, an opening and closing valve flap shaft 11-3 is provided inside the flow limiting nozzle 11, and an opening and closing valve flap 11-4 is provided on the opening and closing valve flap shaft 11-3, a second oil port 11-5 cooperating with the opening and closing valve flap 11-4 is also provided on the flow limiting nozzle 11, and a limiting ring 11-6 for limiting the opening and closing valve flap 11-4 is provided on the outer side of one end of the flow limiting nozzle 11.

[0125] As required, the flow limiting nozzle 11 can be configured as multiple sections, each section having a similar structure. Figure 7 The diagram shows a two-section, single-way open-close flow restrictor structure. Flow restrictor 11 is installed in the first and second oil passages 1-2 and 1-5. Mounting plate 11-1 is installed in conjunction with the first and second oil passages 1-2 and 1-5. The on-off valve shaft 11-3 rotates freely, ensuring the opening and closing of valve 11-4. A limiting ring 11-6 ensures the opening and closing angle of valve 11-4. Based on the marking line, the opening angle is between 30° and 45°. This ensures smooth closing of valve 11-4 when high-pressure hydraulic oil flows in direction b.

[0126] When the high-pressure hydraulic oil flows in direction a, the hydraulic oil flows in from the first oil port 11-2; at the same time, the high-pressure hydraulic oil will push open the opening and closing valve disc 11-4 and flow out from the second oil port 11-5; at this time, the flow limiting valve has a maximum output flow rate, and at the same time has the function of buffering the impulse and flow rate of the high-pressure oil, ensuring the stable input of the high-pressure oil, which is conducive to the stable extension of the hydraulic cylinder.

[0127] When the high-pressure hydraulic oil flows in direction b, the hydraulic oil flows out from the first oil port 11-2; at the same time, the high-pressure hydraulic oil will push the opening and closing valve disc 11-4 and the second oil port 11-5 to close; at this time, the flow limiting valve has a minimum output flow, which has the function of limiting the return oil flow and flow rate. First, it is conducive to the stable retraction of the hydraulic cylinder. Second, when the hydraulic cylinder assembly is in the lifting process and has not yet been locked by the hydraulic mechanical lock, if the hydraulic oil is accidentally depressurized, it can slow down the descent speed of the hydraulic cylinder and improve the safety of the hydraulic cylinder.

[0128] In addition, the up and down movement of the first cylinder piston 2-2 will not affect the matching relationship between the second guide rod 6-1 and the second cylinder piston 3-2, and the same applies to the up and down movement of the second cylinder piston 3-2.

[0129] In addition, if Figure 4 As shown, the first connecting thread 1-9 divides the fixed cylinder body 1-1 into the upper part 1-1 and the lower part 1-1, the second connecting thread 2-11 divides the first-level cylinder body 2-1 into the upper part 2-1 and the lower part 2-1, and the third connecting thread 3-9 divides the second-level cylinder body 3-1 into the upper part 3-1 and the lower part 3-1. A sealing ring should also be provided at the connecting thread, which will not be described in detail.

[0130] The specific assembly method of the hydraulic cylinder of the present invention is as follows (for ease of reading, only reference numerals are used below to represent the various components):

[0131] (1) Install 8, 9, and 10 into 2-2, 3-2, and 4-2 respectively; (2) Install 7-1 and 7-2 into the lower part of 3-1; (3) Install 4-1 and 4-2 as a whole into the lower part of 3-1 and assemble with 7; (4) Thread the lower part of 3-1 to the upper part of 3-1; (5) Install the previous assembly into the lower part of 2-1; (6) Install 6-1 and 6-2 into the lower part of 2-1 and connect them with the lower part of 3-1; (7) Thread the lower part of 2-1 to the upper part of 2-1; (8) Install the above assembly into the lower part of 1-1; (9) Install 5-1 and 5-2 into the lower part of 1-1 and connect them with the lower part of 2-1; (10) Thread the lower part of 1-1 to the upper part of 1-1. From then on, the assembly of the hydraulic cylinder is completed.

[0132] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A multi-stage hydraulic cylinder structure with mechanical and hydraulic double locking, comprising a hydraulic extension rod and a multi-stage cylinder assembly, wherein the multi-stage cylinder assembly comprises a fixed cylinder, wherein a first-stage cylinder extending to the outside is provided inside the fixed cylinder, a second-stage cylinder extending to the outside is provided inside the first-stage cylinder, a hydraulic extension rod extending to the outside is provided inside the second-stage cylinder, a first-stage cylinder piston connected to the bottom of the first-stage cylinder is provided inside the fixed cylinder, a second-stage cylinder piston connected to the bottom of the second-stage cylinder is provided inside the first-stage cylinder, and a third-stage hydraulic piston connected to the bottom of the hydraulic extension rod is provided inside the second-stage cylinder, characterized in that: Also included is a multi-stage guide rod assembly, the multi-stage guide rod assembly comprising: A first-stage guide rod assembly specifically comprises: a first guide rod and a first locking assembly for enabling the first-stage cylinder piston to be locked at the upper and lower ends of the first guide rod, wherein the first locking assembly comprises first bayonet holes provided at the upper and lower ends of the side of the first guide rod and a first hydraulic-mechanical lock assembly for locking or unlocking the first bayonet holes, the first hydraulic-mechanical lock assembly comprising a first mounting bolt mounted on the first-stage cylinder piston, a first sleeve being fixed to the first mounting bolt, a first hydraulic piston being provided on the first sleeve and being capable of sliding within the first sleeve, the first hydraulic piston being connected to the first sleeve via a first spring, and a first sealing rubber ring being provided on the first hydraulic piston; A secondary guide rod assembly, specifically comprising: a second guide rod and a second locking assembly for enabling the secondary cylinder piston to be locked at the upper and lower ends of the second guide rod, wherein the second locking assembly includes second bayonet holes provided at the upper and lower ends of the side of the second guide rod and a second hydraulic-mechanical lock assembly for locking or unlocking the second bayonet holes, the second hydraulic-mechanical lock assembly including a second mounting bolt mounted on the secondary cylinder piston, and a second sleeve fixed on the second mounting bolt, a second hydraulic piston capable of sliding within the second sleeve provided on the second sleeve, the second hydraulic piston and the second sleeve being connected by a second spring, and a second sealing rubber ring provided on the first hydraulic piston; The three-stage guide rod assembly specifically includes: a third guide rod and a third locking assembly for enabling the three-stage hydraulic piston to be locked at the upper and lower ends of the third guide rod, wherein the third locking assembly includes third bayonet holes provided at the upper and lower ends of the side of the third guide rod and a third hydraulic-mechanical lock assembly for locking or unlocking the third bayonet holes, the third hydraulic-mechanical lock assembly includes a third mounting bolt mounted on the three-stage hydraulic piston, and a third sleeve fixed on the third mounting bolt, a third hydraulic piston capable of sliding within the third sleeve provided on the third sleeve, the third hydraulic piston and the third sleeve being connected by a third spring, and a third sealing rubber ring provided on the first hydraulic piston; The set elastic force of the third spring is greater than the set elastic force of the second spring, and the set elastic force of the second spring is greater than the set elastic force of the first spring; The lower chamber of the first-stage cylinder piston, the lower chamber of the second-stage cylinder piston and the lower chamber of the third-stage hydraulic piston are connected through a first oil passage assembly; the first oil passage assembly includes a first oil guide channel provided inside the first-stage cylinder piston and a second oil guide channel provided inside the second-stage cylinder piston, and also includes a first branch pipe channel and a second branch pipe channel provided in the wall of the fixed cylinder body, and a third branch pipe channel and a fourth branch pipe channel provided in the wall of the first-stage cylinder body; a first filler nozzle oil channel communicating with the lower chamber of the first-stage cylinder piston and a second filler nozzle oil channel communicating with the upper chamber of the first-stage cylinder piston are provided on the outer wall of the fixed cylinder body; the first branch pipe channel is used to connect the first filler nozzle oil channel and the first oil guide channel, and the third branch pipe channel is used to connect the first oil guide channel and the second oil guide channel; The first take-off nozzle oil passage and the second take-off nozzle oil passage are both provided with a flow limiting nozzle, one end of the flow limiting nozzle is provided with a mounting baffle which is installed in cooperation with the first take-off nozzle oil passage or the second take-off nozzle oil passage, the flow limiting nozzle is also provided with a first oil port, an opening and closing valve flap shaft is provided inside the flow limiting nozzle, and an opening and closing valve flap is provided on the opening and closing valve flap shaft, the flow limiting nozzle is also provided with a second oil port which cooperates with the opening and closing valve flap, and a limiting ring is provided on the outer side of one end of the flow limiting nozzle for limiting the opening and closing valve flap.

2. The multi-stage hydraulic cylinder structure with mechanical and hydraulic double locking according to claim 1, characterized in that: The first-stage cylinder piston divides the interior of the fixed cylinder body into a first-stage cylinder piston lower chamber and a first-stage cylinder piston upper chamber; the second-stage cylinder piston divides the interior of the first-stage cylinder body into a second-stage cylinder piston lower chamber and a second-stage cylinder piston upper chamber; the third-stage hydraulic piston divides the interior of the second-stage cylinder body into a third-stage hydraulic piston lower chamber and a third-stage hydraulic piston upper chamber.

3. The multi-stage hydraulic cylinder structure with mechanical and hydraulic double locking according to claim 2, characterized in that: The first-stage cylinder piston upper chamber, the second-stage cylinder piston upper chamber and the third-stage hydraulic piston upper chamber are connected through a second oil channel assembly.

4. The multi-stage hydraulic cylinder structure with mechanical and hydraulic double locking according to claim 3, characterized in that: The second oil circuit channel assembly includes a third oil guide channel provided in the wall of the first-stage cylinder body and a fourth oil guide channel provided in the wall of the second-stage cylinder body. The third oil guide channel is used to connect the upper chamber of the first-stage cylinder piston and the upper chamber of the second-stage cylinder piston, and the fourth oil guide channel is used to connect the upper chamber of the second-stage cylinder piston and the upper chamber of the third-stage hydraulic piston.

5. The multi-stage hydraulic cylinder structure with mechanical and hydraulic double locking according to claim 4, characterized in that: A first sealing ring is provided at the connection between the fixed cylinder body and the first-stage cylinder body, a second sealing ring is provided on the outside of the first-stage cylinder piston, a third sealing ring is provided at the connection between the first-stage cylinder body and the second-stage cylinder body, a fourth sealing ring is provided on the outside of the second-stage cylinder piston, a fifth sealing ring is provided at the connection between the second-stage cylinder body and the hydraulic extension rod, and a sixth sealing ring is provided on the outside of the third-stage hydraulic piston.

6. The multi-stage hydraulic cylinder structure with mechanical and hydraulic double locking according to claim 5, characterized in that: The inner wall of the fixed cylinder body is provided with a first limiting boss and a second limiting boss for limiting the piston of the first cylinder, the inner wall of the first cylinder body is provided with a third limiting boss and a fourth limiting boss for limiting the piston of the second cylinder, and the interior of the second cylinder body is provided with a fifth limiting boss and a sixth limiting boss for limiting the third hydraulic piston, the fixed cylinder body is provided with a first connecting thread, the first cylinder body is provided with a second connecting thread, and the second cylinder body is provided with a third connecting thread, and the top of the hydraulic extension rod is connected to a rotary joint through threaded rotation.

7. The multi-stage hydraulic cylinder structure with mechanical and hydraulic double locking according to claim 6, characterized in that: The first-level guide rod assembly also includes a first locking nut provided on the fixed cylinder body, and a first copper gasket is provided at the bottom of the first locking nut, a first oil channel and a second oil channel are provided on the first guide rod, and a first sealing rubber ring is provided on the top of the first locking nut; the second-level guide rod assembly also includes a second locking nut provided on the first-level cylinder piston, and a second copper gasket is provided at the bottom of the second locking nut, a third oil channel and a fourth oil channel are provided on the top of the second guide rod, and a second sealing rubber ring is provided on the top of the second locking nut; the third-level guide rod assembly also includes a third locking nut provided on the second-level cylinder piston, and a third copper gasket is provided at the bottom of the third locking nut, a fifth oil channel and a sixth oil channel are provided on the top of the third guide rod, and a third sealing rubber ring is provided on the top of the third locking nut.

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