Multi-stage maintenance-free hydraulic buffering device and method

Abstract

The invention relates to the technical field of hydraulic buffering, and discloses a multi-stage maintenance-free hydraulic buffering device and method.The multi-stage maintenance-free hydraulic buffering device comprises a buffering base, a liquid cavity corrugated pipe, an air cavity corrugated pipe, a buffering piston and a pressure-bearing outer cylinder; the buffer base, the liquid cavity corrugated pipe and the buffer piston form a second-stage buffer liquid cavity, the buffer piston and the pressure-bearing outer cylinder form a first-stage buffer liquid cavity, the buffer base, the air cavity corrugated pipe and the buffer piston form a third-stage buffer liquid cavity, and the buffer base and the air cavity corrugated pipe form a buffer air cavity; the buffer piston is provided with a plurality of variable cross-section grooves and throttling holes. By utilizing the variable cross-section groove and the buffer air cavity, pressure pulse generated by a medium when the buffer device enters a buffer stage is effectively reduced, and the overall service life of the device is prolonged; by means of the variable cross-section grooves, the throttling holes and the buffering air cavities, multi-redundancy buffering is effectively achieved, and buffering reliability is improved.

Description

Technical Field

[0001] The invention relates to the technical field of hydraulic buffering, in particular to a multi-stage maintenance-free hydraulic buffering device and method. Background Art

[0002] As an actuator that performs linear reciprocating motion, the hydraulic cylinder is prone to violent collision between the piston and the bottom of the cylinder when it moves to the end at high speed, which not only causes abnormal noise and vibration, but also damages other components of the hydraulic system, greatly affecting the life and safety of the hydraulic system. Therefore, the development of hydraulic end buffer devices has attracted much attention. Its main function is to convert the mechanical energy of the moving parts into liquid heat energy for release, thereby extending the life of the hydraulic device and improving safety.

[0003] At present, the traditional hydraulic buffer devices are mainly divided into the following categories: hydraulic buffer, rubber buffer, spring buffer, pneumatic buffer. The above buffer devices have a single buffering method, poor buffering effect, large instantaneous pressure pulse, and are limited by internal space. The buffer devices are also prone to more mechanical structures. At the same time, in actual application, the buffering effect is sometimes not ideal, and it needs to be disassembled, repaired, assembled and debugged, which has the disadvantages of complex operation process, low efficiency and difficult maintenance. Summary of the invention

[0004] The purpose of the present invention is to provide a multi-stage maintenance-free hydraulic buffer device and method to solve the problem that the existing buffer device has a single buffering mode and the pressure pulse generated instantly during buffering is large and damages components.

[0005] The present invention is achieved through the following technical scheme: a multi-stage maintenance-free hydraulic buffer device, including a buffer base, a liquid cavity bellows, an air cavity bellows, a buffer piston, and a pressure-bearing outer cylinder; the liquid cavity bellows, the air cavity bellows, and the buffer piston are all installed on the buffer base, the pressure-bearing outer cylinder is installed on the liquid cavity bellows, and the buffer piston is slidably connected to the pressure-bearing outer cylinder; the buffer base, the liquid cavity bellows, and the buffer piston constitute a secondary buffer cavity, the buffer piston and the pressure-bearing outer cylinder constitute a primary buffer cavity, the buffer base, the air cavity bellows, and the buffer piston constitute a tertiary buffer cavity, and the buffer base and the air cavity bellows constitute a buffer air cavity.

[0006] A buffer chamber one-way valve and a buffer air chamber one-way valve are installed on the buffer base. The buffer chamber one-way valve is located on the tertiary buffer chamber, and the buffer air chamber one-way valve is located on the buffer air chamber. A plurality of variable-section grooves and throttling holes are provided on the buffer piston. The secondary buffer chamber is connected to the tertiary buffer chamber through the throttling hole, and the secondary buffer chamber is connected to the primary buffer chamber through the variable-section groove. The cross-sectional area of ​​one end of the variable-section groove close to the primary buffer chamber is larger than the cross-sectional area of ​​the other end away from the primary buffer chamber.

[0007] In order to better implement the present invention, further, the variable cross-section grooves are evenly spaced in a circumferential array distributed on the circumferential wall surface of the buffer piston.

[0008] In order to better implement the present invention, further, the liquid cavity bellows, the air cavity bellows, the buffer piston, and the pressure-bearing outer cylinder are coaxially arranged.

[0009] In order to better realize the present invention, further, a fourth sealing group is arranged between the liquid cavity bellows and the pressure-bearing outer cylinder, a first sealing group is arranged between the buffer base and the liquid cavity bellows, a sealing smooth surface is arranged on the buffer piston, a second sealing group is arranged between the buffer base and the buffer piston, the second sealing group is on the sealing smooth surface, and a third sealing group is arranged between the buffer base and the air cavity bellows.

[0010] In order to better realize the present invention, further, the liquid chamber bellows is connected to the pressure-bearing outer cylinder through a third thread, the buffer piston is provided with a connecting thread, the buffer base is connected to the connecting thread through a first thread, the buffer base is connected to the air chamber bellows through a second thread, and the buffer base is connected to the liquid chamber bellows through flange bolts and flange nuts.

[0011] In order to better realize the present invention, further, the buffer chamber check valve and the buffer air chamber check valve have the same structure, and are both composed of a retaining ring, a locking nut, a fifth sealing group, a movable slider, a driving spring, a fixed slider, and an oil inlet passage; the movable slider and the fixed slider are slidably connected to the buffer base, a retaining ring is installed on the buffer base, the retaining ring limits the fixed slider, the locking nut is threadedly connected to the buffer base, the locking nut limits the movable slider, the oil inlet passage is arranged on the fixed slider, the driving spring is arranged between the movable slider and the fixed slider, and the fifth sealing group is arranged between the movable slider and the locking nut.

[0012] A multi-stage maintenance-free hydraulic buffer method comprises the following steps:

[0013] A. Inject nitrogen into the buffer air cavity through the buffer air cavity check valve, so that the buffer air cavity has the required pressure; inject oil into the tertiary buffer cavity through the buffer cavity check valve, so that the tertiary buffer cavity, the secondary buffer cavity, and the primary buffer cavity are filled with oil in sequence, and at this time, the pressure-bearing outer cylinder is away from the buffer piston;

[0014] B. Apply external pressure shock to the pressure-bearing outer cylinder, the pressure-bearing outer cylinder approaches the buffer base, the volume of the primary buffer chamber begins to decrease, and the oil in the primary buffer chamber begins to enter the secondary buffer chamber from the variable-section groove, thereby realizing primary buffering; since the pressure-bearing outer cylinder drives the liquid chamber bellows, the liquid chamber bellows begins to deform, the volume of the secondary buffer chamber decreases, and the oil in the secondary buffer chamber enters the tertiary buffer chamber through the throttle hole, thereby realizing secondary buffering; due to the entry of oil into the tertiary buffer chamber, the volume of the tertiary buffer chamber increases, causing the air chamber bellows to begin to deform, the volume of the buffer air chamber begins to shrink accordingly, and the nitrogen in the buffer air chamber is compressed, thereby realizing tertiary buffering;

[0015] C. Remove the external pressure shock, the buffer air cavity begins to expand under the action of air pressure, and the oil returns along the original path. At this time, the tertiary buffer cavity begins to decrease, the secondary buffer cavity and the primary buffer cavity begin to increase, and the pressure-bearing outer cylinder is reset.

[0016] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0017] (1) The present invention utilizes a variable cross-section groove and a buffer air cavity to effectively reduce the pressure pulse generated by the medium when the buffer device enters the buffer stage, thereby increasing the overall life of the device;

[0018] (2) The present invention utilizes variable cross-section grooves, throttling holes, and buffer air cavities to effectively achieve redundant buffering and improve buffering reliability;

[0019] (3) The primary buffer chamber, the secondary buffer chamber, the tertiary buffer chamber, and the buffer gas chamber of the present invention are all closed chambers, which prevent the excess matter caused by the alternation of internal and external media, and realize the maintenance without replacement of the media;

[0020] (4) This device can be used as an external buffer to achieve end buffering for different hydraulic telescopic devices. It is easy to install and operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a cross-sectional view of the overall structure of the present invention.

[0022] Figure 2 Schematic diagram of the buffer piston structure.

[0023] Figure 3 It is a cross-sectional view of the buffer chamber one-way valve and the buffer air chamber one-way valve structure.

[0024] Among them: 10-flange bolt; 11-buffer base; 12-flange nut; 13-first sealing group; 14-buffer chamber one-way valve; 15-second sealing group; 16-first thread fit; 17-third sealing group; 18-buffer air chamber one-way valve; 19-second thread fit; 20-liquid chamber bellows; 21-air chamber bellows; 22-buffer piston; 23-fourth sealing group; 24-third thread fit; 25-pressure-bearing outer cylinder; 26-first buffer chamber; 27-second buffer chamber; 28-third buffer chamber; 29-buffer air chamber; 30-retaining ring; 31-locking nut; 32-fifth sealing group; 33-movable slider; 34-driving spring; 35-fixed slider; 36-oil and air inlet; 221-variable cross-section groove; 222-throttle hole; 223-connecting thread; 224-sealing smooth surface. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions 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 of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0027] Embodiment 1:

[0028] This embodiment provides a multi-stage maintenance-free hydraulic buffer device. Figure 1-Figure 2As shown, it includes a buffer base 11, a liquid cavity bellows 20, an air cavity bellows 21, a buffer piston 22, and a pressure-bearing outer cylinder 25; the liquid cavity bellows 20, the air cavity bellows 21, and the buffer piston 22 are all installed on the buffer base 11, the pressure-bearing outer cylinder 25 is installed on the liquid cavity bellows 20, and the buffer piston 22 is slidably connected with the pressure-bearing outer cylinder 25; the buffer base 11, the liquid cavity bellows 20, and the buffer piston 22 form a secondary buffer cavity 27, the buffer piston 22 and the pressure-bearing outer cylinder 25 form a primary buffer cavity 26, the buffer base 11, the air cavity bellows 21, and the buffer piston 22 form a tertiary buffer cavity 28, the buffer base 11, the air cavity The bellows 21 forms a buffer air cavity 29; a buffer cavity one-way valve 14 and a buffer air cavity one-way valve 18 are installed on the buffer base 11, the buffer cavity one-way valve 14 is located on the tertiary buffer cavity 28, and the buffer air cavity one-way valve 18 is located on the buffer air cavity 29; a plurality of variable-section grooves 221 and throttle holes 222 are provided on the buffer piston 22, the secondary buffer cavity 27 is connected with the tertiary buffer cavity 28 through the throttle hole 222, and the secondary buffer cavity 27 is connected with the primary buffer cavity 26 through the variable-section groove 221; the cross-sectional area of ​​the variable-section groove 221 at one end close to the primary buffer cavity 26 is larger than the cross-sectional area of ​​the end away from the primary buffer cavity 26.

[0029] Based on the above device, a multi-stage maintenance-free hydraulic buffer method is provided, comprising the following steps:

[0030] A. The staff injects nitrogen into the buffer air cavity 29 through the buffer air cavity check valve 18, so that the buffer air cavity 29 has the required pressure; injects oil into the tertiary buffer cavity 28 through the buffer cavity check valve 14, so that the tertiary buffer cavity 28, the secondary buffer cavity 27, and the primary buffer cavity 26 are filled with oil in sequence, and at this time, the pressure-bearing outer cylinder 25 is away from the buffer piston 22;

[0031] B. Apply external pressure shock to the pressure-bearing outer cylinder 25 by using an external mechanism. After the pressure-bearing outer cylinder 25 is subjected to the force, it approaches the buffer base 11, and the volume of the primary buffer chamber 26 begins to decrease. The oil in the primary buffer chamber 26 begins to enter the secondary buffer chamber 27 from the variable cross-section groove 221, thereby realizing primary buffering. Since the cross-sectional size of the variable cross-sectional groove 221 changes linearly, when the pressure-bearing outer cylinder 25 moves, the oil passage will gradually become smaller, and the oil resistance will become larger and larger, thereby realizing the gradual enhancement of the buffering performance and avoiding the damage caused by the sudden drop in speed. Pressure pulse; since the pressure-bearing outer cylinder 25 will also drive the liquid cavity bellows 20 when it moves, the liquid cavity bellows 20 begins to deform, the volume of the secondary buffer cavity 27 decreases, and the oil in the secondary buffer cavity 27 enters the tertiary buffer cavity 28 through the throttle hole 222, thereby realizing secondary buffering; due to the entry of oil into the tertiary buffer cavity 28, the volume of the tertiary buffer cavity 28 begins to gradually increase, causing the air cavity bellows 21 to begin to deform, the volume of the buffer air cavity 29 begins to shrink accordingly, and the nitrogen in the buffer air cavity 29 is compressed, thereby realizing tertiary buffering;

[0032] C. Remove the external pressure shock, the buffer air cavity 29 begins to expand under the action of air pressure, and the oil returns along the original path. At this time, the tertiary buffer cavity 28 begins to decrease, the secondary buffer cavity 27 and the primary buffer cavity 26 begin to increase, and the pressure-bearing outer cylinder 25 returns to its original position.

[0033] Through the above-mentioned arrangement, the variable cross-section groove 221 and the buffer air cavity 29 are utilized to effectively reduce the pressure pulse generated by the medium when the buffer device enters the buffer stage; the variable cross-section groove 221, the throttle hole 222, and the buffer air cavity 29 are utilized to effectively realize redundant buffering and improve the reliability of buffering; the first-level buffer cavity 26, the second-level buffer cavity 27, the third-level buffer cavity 28, and the buffer air cavity 29 are all closed cavities to prevent excess materials caused by the alternation of internal and external media, and realize the maintenance-free replacement of the medium; and the device can be used as an external buffer, which can realize end buffering for different hydraulic telescopic devices, and is easy to install and operate.

[0034] The other parts of this embodiment are the same as those of the above embodiment and will not be described in detail.

[0035] Embodiment 2:

[0036] This embodiment further defines the position of the variable cross-section groove 221 based on the above embodiment. Figure 2 As shown, the variable cross-section grooves 221 are distributed in an equidistant circular array on the circumferential wall surface of the buffer piston 22 .

[0037] By evenly distributing the variable-section grooves 221, when the pressure-bearing outer cylinder 25 is under pressure, the oil can evenly flow from the variable-section grooves 221 into the secondary buffer chamber 27, so that the pressure-bearing outer cylinder 25 is evenly stressed, preventing the torque from deviating from the axis due to the uneven setting of the variable-section grooves 221, thereby increasing wear.

[0038] The other parts of this embodiment are the same as those of the above embodiment and will not be described in detail.

[0039] Embodiment 3:

[0040] This embodiment is further limited on the basis of the above embodiment. Figure 1 As shown, the liquid cavity bellows 20, the air cavity bellows 21, the buffer piston 22, and the pressure-bearing outer cylinder 25 are coaxially arranged.

[0041] This arrangement allows the secondary buffer chamber 27 to evenly surround the buffer piston 22; the tertiary buffer chamber 28 to evenly surround the buffer air chamber 29. When the volumes of the secondary buffer chamber 27 and the buffer air chamber 29 change, the deformation of the liquid chamber bellows 20 and the air chamber bellows 21 are even, thereby preventing the liquid chamber bellows 20 and the air chamber bellows 21 from being shortened due to stress concentration caused by excessive local deformation.

[0042] The other parts of this embodiment are the same as those of the above embodiment and will not be described in detail.

[0043] Embodiment 4:

[0044] This embodiment is further limited on the basis of the above embodiment. Figure 1 As shown, a fourth sealing group 23 is arranged between the liquid cavity bellows 20 and the pressure-bearing outer cylinder 25, a first sealing group 13 is arranged between the buffer base 11 and the liquid cavity bellows 20, a sealing smooth surface 224 is arranged on the buffer piston 22, a second sealing group 15 is arranged between the buffer base 11 and the buffer piston 22, and the second sealing group 15 is on the sealing smooth surface 224, and a third sealing group 17 is arranged between the buffer base 11 and the air cavity bellows 21.

[0045] Through the above-mentioned arrangement, the sealing performance of the primary buffer chamber 26, the secondary buffer chamber 27, the tertiary buffer chamber 28, and the buffer air chamber 29 is improved. On the one hand, it prevents external media from entering the interior, which leads to an increase in the maintenance frequency; on the other hand, it further improves the sealing performance of the primary buffer chamber 26, the secondary buffer chamber 27, the tertiary buffer chamber 28, and the buffer air chamber 29 to prevent uncontrollable pressure release during the buffering stage, which leads to buffering failure.

[0046] The other parts of this embodiment are the same as those of the above embodiment and will not be described in detail.

[0047] Embodiment 5:

[0048] This embodiment is further limited on the basis of the above embodiment. Figure 1 As shown, the liquid cavity bellows 20 is connected to the pressure-bearing outer cylinder 25 through a third threaded fit 24, a connecting thread 223 is provided on the buffer piston 22, the buffer base 11 is connected to the connecting thread 223 through a first threaded fit 16, the buffer base 11 is connected to the air cavity bellows 21 through a second threaded fit 19, the buffer base 11 is connected to the liquid cavity bellows 20 through a flange bolt 10 and a flange nut 12, and the flange bolt 10 and the flange nut 12 are locked to fix the buffer base 11 and the liquid cavity bellows 20.

[0049] Through the above arrangement, the quick connection of the thread is utilized to facilitate disassembly and assembly during maintenance and repair of the device; at the same time, the threaded connection has good stability to prevent connection failure.

[0050] The other parts of this embodiment are the same as those of the above embodiment and will not be described in detail.

[0051] Embodiment 6:

[0052] This embodiment further expands the buffer chamber check valve 14 and the buffer air chamber check valve 18 on the basis of the above embodiment. Figure 3 As shown, the buffer chamber one-way valve 14 and the buffer air chamber one-way valve 18 have the same structure, and are both composed of a retaining ring 30, a locking nut 31, a fifth sealing group 32, a movable slider 33, a driving spring 34, a fixed slider 35, and an oil inlet passage 36; the movable slider 33 and the fixed slider 35 are slidably connected to the buffer base 11, and the retaining ring 30 is installed on the buffer base 11, and the retaining ring 30 limits the fixed slider 35. The locking nut 31 is threadedly connected to the buffer base 11, and the locking nut 31 limits the movable slider 33. The oil inlet passage 36 is arranged on the fixed slider 35, and the driving spring 34 is arranged between the movable slider 33 and the fixed slider 35. The fifth sealing group 32 is arranged between the movable slider 33 and the locking nut 31.

[0053] When nitrogen is filled into one end of the locking nut 31, when the air pressure at one end of the locking nut 31 is greater than the sum of the elastic force of the driving spring 34 and the air pressure in the buffer air chamber 29, the driving spring 34 is squeezed, and the moving slider 33 is separated from the locking nut 31. At this time, the gas flows through the gap between the locking nut 31 and the moving slider 33, and flows into the buffer air chamber 29 through the oil inlet duct 36. When there is no air pressure at the end of the locking nut 31, under the action of the air pressure in the buffer air chamber 29 and the elastic force of the driving spring 34, the moving slider 33 is pressed on the locking nut 31 and sealed by the fifth sealing group 32. At this time, the gas in the buffer air chamber 29 cannot flow out from the locking nut 31; if oil is filled into the end of the locking nut 31, the distance is the same as the above description and will not be repeated. The initial pressures of the first-level buffer chamber 26, the second-level buffer chamber 27, and the third-level buffer chamber 28 are controlled by the buffer chamber one-way valve 14, and the initial pressure of the buffer air chamber 29 is controlled by the buffer air chamber one-way valve 18, so as to adjust the overall pressure of the entire device to buffer scenes with different impact intensities.

[0054] The other parts of this embodiment are the same as those of the above embodiment and will not be described in detail.

[0055] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent change made to the above embodiment based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A multi-stage maintenance-free hydraulic buffer device, characterized in that: The invention comprises a buffer base (11), a liquid cavity bellows (20), an air cavity bellows (21), a buffer piston (22), and a pressure-bearing outer cylinder (25); the liquid cavity bellows (20), the air cavity bellows (21), and the buffer piston (22) are all mounted on the buffer base (11), the pressure-bearing outer cylinder (25) is mounted on the liquid cavity bellows (20), and the buffer piston (22) is slidably connected to the pressure-bearing outer cylinder (25); the buffer base (11), the liquid cavity bellows (20), and the buffer piston (22) form a secondary buffer cavity (27), the buffer piston (22) and the pressure-bearing outer cylinder (25) form a primary buffer cavity (26), the buffer base (11), the air cavity bellows (21), and the buffer piston (22) form a tertiary buffer cavity (28), and the buffer base (11) and the air cavity bellows (21) form a buffer gas cavity (29); The buffer base (11) is provided with a buffer chamber check valve (14) and a buffer air chamber check valve (18); the buffer chamber check valve (14) is located on the tertiary buffer chamber (28), and the buffer air chamber check valve (18) is located on the buffer air chamber (29); the buffer piston (22) is provided with a plurality of variable cross-section grooves (221) and throttle holes (222); the secondary buffer chamber (27) is connected to the tertiary buffer chamber (28) through the throttle holes (222), and the secondary buffer chamber (27) is connected to the primary buffer chamber (26) through the variable cross-section groove (221); the cross-sectional area of ​​one end of the variable cross-section groove (221) close to the primary buffer chamber (26) is greater than the cross-sectional area of ​​the other end away from the primary buffer chamber (26).

2. A multi-stage maintenance-free hydraulic buffer device according to claim 1, characterized in that: The variable cross-section grooves (221) are distributed in an equidistant circumferential array on the circumferential wall surface of the buffer piston (22).

3. A multi-stage maintenance-free hydraulic buffer device according to claim 1, characterized in that: The liquid cavity bellows (20), the air cavity bellows (21), the buffer piston (22), and the pressure-bearing outer cylinder (25) are coaxially arranged.

4. The multi-stage maintenance-free hydraulic buffer device according to claim 1, characterized in that: A fourth sealing group (23) is arranged between the liquid cavity bellows (20) and the pressure-bearing outer cylinder (25), a first sealing group (13) is arranged between the buffer base (11) and the liquid cavity bellows (20), a sealing smooth surface (224) is arranged on the buffer piston (22), a second sealing group (15) is arranged between the buffer base (11) and the buffer piston (22), and the second sealing group (15) is located on the sealing smooth surface (224), and a third sealing group (17) is arranged between the buffer base (11) and the air cavity bellows (21).

5. The multi-stage maintenance-free hydraulic buffer device according to claim 1, characterized in that: The liquid cavity bellows (20) is connected to the pressure-bearing outer cylinder (25) via a third threaded fit (24); a connecting thread (223) is provided on the buffer piston (22); the buffer base (11) is connected to the connecting thread (223) via a first threaded fit (16); the buffer base (11) is connected to the air cavity bellows (21) via a second threaded fit (19); and the buffer base (11) is connected to the liquid cavity bellows (20) via a flange bolt (10) and a flange nut (12).

6. The multi-stage maintenance-free hydraulic buffer device according to claim 1, characterized in that: The buffer chamber check valve (14) and the buffer air chamber check valve (18) have the same structure, and are both composed of a clamping ring (30), a locking nut (31), a fifth sealing group (32), a movable slider (33), a driving spring (34), a fixed slider (35), and an oil inlet passage (36); the movable slider (33) and the fixed slider (35) are slidably connected to the buffer base (11), the clamping ring (30) is installed on the buffer base (11), the clamping ring (30) limits the fixed slider (35), the locking nut (31) is threadedly connected to the buffer base (11), the locking nut (31) limits the movable slider (33), the oil inlet passage (36) is arranged on the fixed slider (35), the driving spring (34) is arranged between the movable slider (33) and the fixed slider (35), and the fifth sealing group (32) is arranged between the movable slider (33) and the locking nut (31).

7. A multi-stage maintenance-free hydraulic buffer method, using the device according to any one of claims 1 to 6, characterized in that: The steps include: A. Nitrogen is injected into the buffer air cavity (29) through the buffer air cavity one-way valve (18) so that the buffer air cavity (29) has the required pressure; oil is injected into the tertiary buffer cavity (28) through the buffer cavity one-way valve (14) so ​​that the tertiary buffer cavity (28), the secondary buffer cavity (27) and the primary buffer cavity (26) are filled with oil in sequence, and at this time, the pressure-bearing outer cylinder (25) is in a state of being away from the buffer piston (22); B. Applying external pressure shock to the pressure-bearing outer cylinder (25), the pressure-bearing outer cylinder (25) approaches the buffer base (11), the volume of the primary buffer chamber (26) begins to decrease, and the oil in the primary buffer chamber (26) begins to enter the secondary buffer chamber (27) from the variable cross-section groove (221), thereby realizing primary buffering; since the pressure-bearing outer cylinder (25) drives the liquid chamber bellows (20), the liquid chamber bellows (20) begins to deform, the volume of the secondary buffer chamber (27) decreases, and the oil in the secondary buffer chamber (27) enters the tertiary buffer chamber (28) through the throttle hole (222), thereby realizing secondary buffering; since the oil enters the tertiary buffer chamber (28), the volume of the tertiary buffer chamber (28) increases, causing the air chamber bellows (21) to begin to deform, the volume of the buffer air chamber (29) begins to decrease accordingly, and the nitrogen in the buffer air chamber (29) is compressed, thereby realizing tertiary buffering; C. When the external pressure shock is removed, the buffer air cavity (29) begins to expand under the action of air pressure, and the oil returns along the original path. At this time, the tertiary buffer cavity (28) begins to decrease, the secondary buffer cavity (27) and the primary buffer cavity (26) begin to increase, and the pressure-bearing outer cylinder (25) is reset.

Images