Hydraulic damper

Abstract

A hydraulic damper comprises a cylinder body and a damping assembly arranged in the cylinder body in a telescopic mode, the damping assembly comprises a piston body, the piston body divides an inner cavity of the cylinder body into a first oil cavity and a second oil cavity which are communicated with each other, a first elastic piece and a second elastic piece are arranged on the piston body, the first elastic piece is located on the first oil cavity, and the second elastic piece is located on the second oil cavity. A first channel communicated with the second oil cavity is arranged between the piston body and the second elastic piece, the first elastic piece seals the first channel, a second channel communicated with the first oil cavity is arranged between the piston body and the first elastic piece, and the second elastic piece seals the second channel. According to the hydraulic damper, when the damping assembly is compressed with large force, oil pressure of the second oil cavity acts on the first elastic piece through the first channel so that the first elastic piece can deform elastically and open the first channel, and the second oil cavity is communicated with the first oil cavity through the first channel, so that the number of damping flow channels is increased, and rapid pressure unloading is achieved; and the product or the damper is prevented from being damaged by too high pressure.

Description

TECHNICAL FIELD

[0001] The utility model relates to damper technical field, especially a kind of hydraulic damper. BACKGROUND

[0002] The existing hydraulic damper has the following shortcomings: 1, damper compression, due to the lack of effective pressure unloading mechanism, easy to cause hydraulic damper structure or product (product connected with damper) damage; 2, in the existing hydraulic damper contraction and pull out state conversion, there will be a section of no-damping movement empty stroke, because in the instant of reversal, the flow state of hydraulic oil mutates, leading to damping force cannot be established in time, so that product is in no-damping movement state in short distance, affect the stability of movement and control accuracy; 3, due to the error accumulation of various factors such as machining precision, assembly process during hydraulic damper production process, the actual movement speed and damping size of different dampers exist obvious difference, even if it is the same batch of products, its performance under the same working condition is difficult to achieve high consistency, which brings great trouble for the application scene needing high-precision control, such as shock absorption and stable control of precision instrument.

[0003] Therefore, it is necessary to make further improvement. CONTENT OF UTILITY MODEL

[0004] The utility model discloses a kind of hydraulic dampers with simple structure, easy to adjust, high reliability, can eliminate no-damping phenomenon, practicality is strong, to overcome the deficiencies of prior art.

[0005] A kind of hydraulic damper designed according to this purpose, including cylinder and retractable damper assembly in cylinder, damper assembly includes piston body, piston body separates the inner cavity of cylinder into first oil cavity and second oil cavity, which are interconnected, characterized by: first spring and second spring are arranged on piston body, first spring is located on first oil cavity, second spring is located on second oil cavity, first channel is arranged between piston body and second spring, and the first channel is communicated with second oil cavity, first spring closes first channel, second channel is arranged between piston body and first spring, and the second channel is communicated with first oil cavity, and second spring closes second channel;

[0006] When damper assembly is compressed with great force, oil pressure of second oil cavity acts on first spring through first channel, so that first spring is elastically deformed and opens first channel, and second oil cavity is communicated with first oil cavity through first channel;When damper assembly stops compression, first spring is elastically reset to close first channel;

[0007] When the damping assembly is stretched, the oil pressure of the first oil cavity acts on the second elastic sheet through the second channel to make the second elastic sheet elastically deform and open the second channel, so that the first oil cavity communicates with the second oil cavity through the second channel; when the damping assembly is compressed, the second elastic sheet elastically resets to close the second channel.

[0008] The second oil cavity is provided with a movable piston assembly, the movable piston assembly comprising a movable piston and an elastic member, the elastic member being arranged between the movable piston and the cylinder body; when the damping assembly is stretched, the movable piston moves upward under the elastic force of the elastic member; when the damping assembly is compressed, the movable piston is acted on to move downward and compress the elastic member, so that the damping oil in the second oil cavity is kept in a full state.

[0009] The first seal ring and the first gap are arranged between the piston body and the cylinder body, the first gap respectively communicating the first oil cavity and the second oil cavity, the first seal ring being located in the middle of the first gap, and the inner side of the cylinder body being provided with one or more oil passing grooves; the first seal ring moves up and down when the damping assembly stretches and contracts; when the first seal ring moves to a position not in the oil passing groove, the first seal ring closes the first gap; when the first seal ring moves to a position in the oil passing groove, the first oil cavity communicates with the second oil cavity through the first gap and the oil passing groove.

[0010] The piston body comprises a first piston and a second piston arranged in sequence and relatively rotating, the first elastic sheet being arranged on the top of the first piston, and the second elastic sheet being arranged between the first piston and the second piston; the first piston is provided with a first through hole and a second through hole, the first elastic sheet is provided with a third through hole, the second elastic sheet is provided with a fourth through hole, the first through hole communicates with the fourth through hole to form a first channel, the fourth through hole communicates with the second oil cavity, the second through hole communicates with the third through hole to form a second channel, and the third through hole communicates with the first oil cavity.

[0011] The first piston is provided with a fifth through hole communicating with the first oil cavity, the second piston is provided with a sixth through hole communicating with the second oil cavity, and an intermediate flow channel is arranged between the first piston and the second piston, the fifth through hole communicating with the sixth through hole through the intermediate flow channel, and the length of the intermediate flow channel being adjustable when the first piston and the second piston relatively rotate.

[0012] The second piston is provided with an arc-shaped flow channel, one end of the flow channel communicating with the sixth through hole, and the fifth through hole relatively sliding along the flow channel when the first piston and the second piston relatively rotate, the part of the flow channel through which the fifth through hole and the sixth through hole pass constituting the intermediate flow channel.

[0013] The first piston is annularly provided with a plurality of adjusting holes with different diameters, the adjusting holes communicating with the first oil cavity, the second piston is provided with a sixth through hole communicating with the second oil cavity, the sixth through hole constituting the intermediate flow channel when communicating with the adjusting hole, and the first piston and the second piston relatively rotating to rotate to the position of different adjusting holes through the sixth through hole to adjust the size of the intermediate flow channel.

[0014] The first piston is provided with a fifth through hole communicating with the first oil cavity, the second spring sheet is provided with a seventh through hole communicating with the fifth through hole, the second piston is provided with a slope with a gradually changing height, a second gap is left between the slope and the seventh through hole, the seventh through hole communicates with the second oil cavity through the second gap, the fifth through hole, the seventh through hole and the second gap constitute an intermediate flow channel, and the size of the second gap is adjusted when the first piston and the second piston rotate relatively, so that the size of the intermediate flow channel is adjusted.

[0015] The damping assembly further comprises a piston shaft, the piston shaft passes through the first piston and the second piston, the piston shaft is fixedly connected with the second piston, the piston shaft is in rotational cooperation with the first piston, and the piston shaft drives the second piston to rotate when the piston shaft rotates, so that the first piston and the second piston rotate relatively.

[0016] The first piston is in a non-circular shape, the inner cavity is in a non-circular shape, the first piston is fixed on the inner cavity, the second piston is in a circular shape, and the second piston is rotatably arranged on the inner cavity.

[0017] Further comprising a cover body, the cover body is fixed on the top end of the cylinder body, the piston shaft extends out of the cylinder body after passing through the cover body, a sealing assembly is arranged below the cover body, the sealing assembly is sleeved on the piston shaft, and the piston body is movably limited up and down on the inner cavity.

[0018] The hydraulic damper has the following beneficial effects:

[0019] 1. By arranging the first spring sheet and the second spring sheet on the piston body, the first channel communicating with the second oil cavity is arranged between the piston body and the second spring sheet, the second channel communicating with the first oil cavity is arranged between the piston body and the first spring sheet, when the damping assembly is compressed with great force, the oil pressure of the second oil cavity acts on the first spring sheet through the first channel, so that the first spring sheet is elastically deformed and the first channel is opened, the second oil cavity is communicated with the first oil cavity through the first channel, thereby increasing the flow channel of the damping, realizing rapid pressure unloading, effectively reducing the pressure peak value in the damper, and preventing damage to the product or the damper itself caused by excessive pressure;

[0020] 2. By the assistance of the first spring sheet and the second spring sheet and the cooperation of the first sealing ring and the piston body, the undamped phenomenon of the damper during the conversion between the compression and extension states is basically completely eliminated, the damping force can realize smooth transition during the reversing process, the continuity and stability of product movement are ensured, and the control accuracy and reliability of the system are improved;

[0021] 3. The adjustable intermediate flow channel is arranged between the first piston and the second piston, thereby changing the flow speed and resistance of the damping oil, so as to realize accurate adjustment of the damping speed and size, meet diversified needs of damping in different application scenarios, and meet accurate damping adjustment needs in different working conditions through simple operation (rotating the piston shaft) for precise instruments requiring fine control and heavy mechanical equipment requiring high damping, thereby greatly improving the adaptability and working efficiency of the equipment.

[0022] 4. The cylinder body can be provided with a plurality of different oil passing flow channels (oil passing grooves), different damping in different motion stages can be controlled according to different needs, and the damping speed is different. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 It is a sectional view of the hydraulic damper in the first embodiment of the utility model.

[0024] Figure 2 It is another sectional view of the hydraulic damper in the first embodiment of the utility model.

[0025] Figure 3 It is a whole structure schematic view of the hydraulic damper in the first embodiment of the utility model.

[0026] Figure 4 It is an exploded structure schematic view of the hydraulic damper in the third embodiment of the utility model.

[0027] Figure 5 It is a sectional view of the damping assembly in the first embodiment of the utility model.

[0028] Figure 6 It is an exploded structure schematic view of the damping assembly in the first embodiment of the utility model.

[0029] Figure 7 It is a sectional view of the damping assembly in the second embodiment of the utility model.

[0030] Figure 8 It is an exploded structure schematic view of the damping assembly in the second embodiment of the utility model.

[0031] Figure 9 It is a sectional view of the damping assembly in the third embodiment of the utility model.

[0032] Figure 10 It is an exploded structure schematic view of the damping assembly in the third embodiment of the utility model.

[0033] Figure 11 It is a whole structure schematic view of the damping assembly in the first embodiment of the utility model.

[0034] Figure 12The utility model discloses an embodiment of the whole structure schematic diagram of the cylinder body. DETAILED DESCRIPTION

[0035] The utility model will be further described below in combination with the drawings and examples.

[0036] First embodiment:

[0037] Referring to Figures 1-3 、 Figures 5-6 、 Figures 11-12 The hydraulic damper comprises a cylinder body 1 and a damping assembly A arranged in the cylinder body 1 in an extendable and retractable manner, the damping assembly A comprises a piston body, the piston body divides an inner cavity B of the cylinder body 1 into a first oil cavity 2 and a second oil cavity 3 which are in communication with each other, the piston body is provided with a first elastic sheet 4 and a second elastic sheet 5, the first elastic sheet 4 is located on the first oil cavity 2, the second elastic sheet 5 is located on the second oil cavity 3, a first channel 6 which communicates with the second oil cavity 3 is arranged between the piston body and the second elastic sheet 5, the first elastic sheet 4 closes the first channel 6, a second channel 7 which communicates with the first oil cavity 2 is arranged between the piston body and the first elastic sheet 4, and the second elastic sheet 5 closes the second channel 7.

[0038] When the damping assembly A is compressed with great force, the oil pressure of the second oil cavity 3 acts on the first elastic sheet 4 through the first channel 6, so that the first elastic sheet 4 is elastically deformed and the first channel 6 is opened, the second oil cavity 3 is communicated with the first oil cavity 2 through the first channel 6, and then the damping oil in the second oil cavity 3 can flow to the first oil cavity 2 through the first channel 6, so as to increase the flow channel of the damping, realize pressure unloading, and prevent the damper itself and the product from being damaged; when the compression force of the damping assembly A is reduced, the first elastic sheet 4 is elastically reset to close the first channel 6, so as to maintain a certain damping; the first elastic sheet 4 has relatively large elastic force and large deformation force.

[0039] When the damping assembly A is pulled out, the oil pressure of the first oil cavity 2 acts on the second elastic sheet 5 through the second channel 7, so that the second elastic sheet 5 is elastically deformed and the second channel 7 is opened, the first oil cavity 2 is communicated with the second oil cavity 3 through the second channel 7, and then the damping oil in the first oil cavity 2 can quickly flow to the second oil cavity 3 through the second channel 7, the damping is small, and the second elastic sheet 5 has relatively small elastic force; when the damping assembly A stops being pulled out, the second elastic sheet 5 is elastically reset to close the second channel 7.

[0040] The first elastic sheet 4 is made of special alloy material with high elastic limit and good fatigue performance, and is subjected to precise heat treatment process to ensure stable elastic performance under different temperature and stress conditions. When the damping assembly A is compressed by large force, the first elastic sheet 4 will be deformed under the combined action of oil pressure and mechanical force, and the deformation degree is related to the size of the external force. The deformation of the elastic sheet will expand the originally narrow damping oil flow passage, increase the flow path and cross-sectional area of the damping oil, thereby realizing rapid pressure relief, effectively reducing the pressure peak in the damper, and preventing damage to the product caused by excessive pressure. When the external force decreases, the first elastic sheet 4 quickly resets to the initial state by its own elasticity, continues to maintain a certain damping force, and maintains damping.

[0041] The second elastic sheet 5 has a special shape and elastic coefficient in structural design. When the damping assembly A is pulled out, the second elastic sheet 5 will be deformed and opened under the action of oil pressure, forming a larger flow channel, so that the damping oil can pass quickly. At this time, the damping is small, which is convenient for the quick pull-out operation of the damping assembly A, and improves the response speed of the damper. When the piston stops pulling out, the second elastic sheet 5 will quickly reset in a very short time to restore the sealing state and prevent hydraulic oil leakage, ensuring the stability and reliability of the damper and the normal operation of the damper.

[0042] Short time, restore the sealing state to prevent hydraulic oil leakage, ensure the stability and reliability of the damper and the normal operation of the damper.

[0043] The bottom of the second oil cavity 3 is provided with a movable piston assembly, which includes a movable piston 8 and an elastic member 9. The elastic member 9 is a spring, and is arranged between the movable piston 8 and the cylinder body 1. When the damping assembly A is pulled out, the movable piston 8 moves upward under the elastic force of the elastic member 9 to adjust the full oil in the second oil cavity 3, so that the damping oil in the second oil cavity 3 is always filled to prevent the damping assembly A from jumping when reversing. When the damping assembly A is compressed, it acts on the movable piston 8 to move the movable piston 8 downward and compress the elastic member 9.

[0044] The first sealing ring 10 is arranged between the piston body (the first piston 13) and the cylinder body 1, and the first gap 11 is respectively communicated with the first oil cavity 2 and the second oil cavity 3, the first sealing ring 10 is located in the middle of the first gap 11, and the inner side of the cylinder body 1 is provided with one or more than one oil passing groove 12, when the oil passing grooves 12 are provided in multiple, the oil passing grooves 12 can be annularly distributed on the inner side of the cylinder body 1, or can be distributed on the inner side of the cylinder body 1 in an up-down manner, the oil passing grooves 12 of the embodiment are annularly distributed in two groups, and are distributed in two groups in an up-down manner; the first sealing ring 10 is driven to move up and down by the damping assembly A, when the first sealing ring 10 moves to the position of the non-oil passing groove 12, the first sealing ring 10 seals the first gap 11, at this time, the damping assembly A has a certain resistance when being stretched and contracted, when the first sealing ring 10 moves to the position of the oil passing groove 12, the first oil cavity 2 is communicated with the second oil cavity 3 through the first gap 11 and the oil passing groove 12, at this time, the resistance of the damping assembly A when being stretched and contracted is greatly reduced, the structure can adjust the damping size of the damping assembly A in the stretching and contracting process; in addition, the damping size of the damping assembly A in the stretching and contracting process can be changed according to the requirements of the use scene.

[0045] The piston body comprises the first piston 13 and the second piston 14 arranged in an up-down manner and relatively rotating, the first elastic sheet 4 is arranged on the top of the first piston 13, the second elastic sheet 5 is arranged between the first piston 13 and the second piston 14, the first piston 13 is provided with the first through hole 15 and the second through hole 16, the first elastic sheet 4 is provided with the third through hole 17, the second elastic sheet 5 is provided with the fourth through hole 18, the first through hole 15 is communicated with the fourth through hole 18 and forms the first channel 6, the fourth through hole 18 is communicated with the second oil cavity 3, the second through hole 16 is communicated with the third through hole 17 and forms the second channel 7, and the third through hole 17 is communicated with the first oil cavity 2.

[0046] The first piston 13 is provided with the fifth through hole 19 communicated with the first oil cavity 2, the second piston 14 is provided with the sixth through hole 20 communicated with the second oil cavity 3, and the intermediate flow channel is arranged between the first piston 13 and the second piston 14, the fifth through hole 19 is communicated with the sixth through hole 20 through the intermediate flow channel, and the length of the intermediate flow channel can be adjusted when the first piston 13 and the second piston 14 relatively rotate; thereby changing the flow speed and the size of the resistance of the damping oil, the greater the length of the intermediate flow channel, the smaller the flow speed of the damping oil, and the greater the damping force, the smaller the length of the intermediate flow channel, the greater the flow speed of the damping oil, and the smaller the damping force; the structure can realize stepless adjustment of the damping force.

[0047] The second piston 14 is provided with the circular-arc-shaped flow channel 21, one end of the flow channel 21 is communicated with the sixth through hole 20, the fifth through hole 19 relatively slides along the flow channel 21 when the first piston 13 and the second piston 14 relatively rotate, and the part of the flow channel 21 through which the fifth through hole 19 and the sixth through hole 20 pass constitutes the intermediate flow channel.

[0048] The first elastic sheet 4 is provided with an eighth through hole 28, the second elastic sheet 5 is provided with a ninth through hole 29, the fifth through hole 19 is communicated with the first oil cavity 2 through the eighth through hole 28, and the fifth through hole 19 is communicated with the intermediate flow channel through the ninth through hole 29.

[0049] The damping assembly A further comprises a piston shaft 26 penetrating the first piston 13 and the second piston 14, the piston shaft 26 is fixedly connected with the second piston 14, the piston shaft 26 is rotationally matched with the first piston 13, the piston shaft 26 drives the second piston 14 to rotate when rotating, so that the first piston 13 and the second piston 14 rotate relatively; the piston shaft 26 is manually rotated;

[0050] The piston shaft 26 comprises a circular first shaft body 30 and a non-circular second shaft body 31, the first piston 13 is provided with a circular rotating hole 32, the second piston 14 is provided with a non-circular connecting hole 33, the first shaft body 30 is rotationally matched with the rotating hole 32, and the second shaft body 31 is inserted with the connecting hole 33.

[0051] The first piston 13 is non-circular in shape, the inner cavity B is non-circular in shape, the first piston 13 is fixed on the inner cavity B, the first piston 13 is matched with the inner cavity B, and the first piston 13 and the inner cavity B do not rotate relatively, the second piston 14 is circular in shape, and the second piston 14 is rotationally arranged on the inner cavity B.

[0052] Further comprising a cover body 27 fixed on the top end of the cylinder body 1, the piston shaft 26 extends out of the cylinder body 1 after penetrating the cover body 27, a sealing assembly is arranged below the cover body 27, the sealing assembly is sleeved on the piston shaft 26, the piston body is limited to move up and down on the inner cavity B, the damping assembly A is limited on the sealing assembly when being pulled out upwardly, the sealing assembly is arranged between the piston shaft 26 and the cylinder body 1, and the sealing assembly comprises a second sealing ring 34 and a gasket 35 arranged above and below, the second sealing ring 34 plays a sealing role and prevents the damping oil from leaking out of the cylinder body 1; by optimizing the structural design of the piston body and the cylinder body 1 and reasonably arranging the position and number of the sealing ring, it is ensured that the sealing ring can always maintain a stable sealing state during the reversing process of the damper, and the phenomenon of stringing is avoided.

[0053] The first piston 13 is provided with a sealing groove 36, and the first sealing ring 10 is sleeved on the sealing groove 36.

[0054] The second shaft body 31 is provided with a first gasket 37 and a second gasket 38 at the upper end and the lower end respectively, the first elastic sheet 4 is pressed between the first gasket 37 and the first piston 13, and the second gasket 38 is located at the bottom of the second piston 14.

[0055] The existing hydraulic dampers change the speed during the movement of the product due to the temperature changes in spring, summer, autumn and winter, the speed is fast when the temperature is high and the damping is small, and the speed is slow when the temperature is low and the damping is large; the hydraulic damper can effectively reduce the influence of temperature change on damping performance through careful selection of damping oil and unique structural design. The speed change rate of the damer is reduced by more than 80% compared with the traditional hydraulic damper in a wide temperature range (for example, -40℃ to 120℃), which can maintain a relatively stable damping force output, and provides a strong guarantee for the reliable operation of the equipment under different environmental temperatures, especially for equipment working in extreme climate conditions, such as aerospace equipment, field operation machinery, etc.

[0056] The hydraulic damper can flexibly set the segmented resistance according to the specific application requirements; through the structural design of the first piston 13 and the second piston 14 and the control of the damping adjustment mechanism, the size of the damping can change according to the preset rule during the movement of the piston; for example, a smaller damping is set during the starting stage of the equipment, which facilitates fast starting; during the running process, the damping size is automatically adjusted according to the load change to ensure the stability of the running; during the stopping stage, the damping is increased to realize rapid braking; this segmented resistance setting function further expands the application range of the damper and improves the intelligentization and self-adaptation ability of the equipment.

[0057] The hydraulic damper can be applied to hinges and other fields such as equipment.

[0058] Second embodiment:

[0059] Referring to Figures 7-8 , the hydraulic damper differs from the first embodiment in that:

[0060] The first piston 13 is annularly and uniformly provided with a plurality of adjustment holes 22 of different diameters, the adjustment holes 22 are communicated with the first oil cavity 2, the second piston 14 is provided with a sixth through hole 20 communicated with the second oil cavity 3, and the sixth through hole 20 and the adjustment hole 22 form an intermediate flow passage when communicated. When the first piston 13 and the second piston 14 rotate relative to each other, the sixth through hole 20 is rotated to the position of different adjustment holes 22 to adjust the size of the intermediate flow passage, and then the flow speed and the size of the resistance of the damping oil are changed. The larger the intermediate flow passage, the greater the flow speed of the damping oil, and the smaller the damping force. The smaller the intermediate flow passage, the smaller the flow speed of the damping oil, and the greater the damping force. This structure can realize step (gear) adjustment of the damping force.

[0061] The first spring 4 is annularly and uniformly provided with a plurality of tenth through holes 39, and the second spring 5 is annularly and uniformly provided with a plurality of eleventh through holes 40. The adjustment hole 22 is communicated with the first oil cavity 2 through the tenth through hole 39, and the adjustment hole 22 is communicated with the sixth through hole 20 through the eleventh through hole 40.

[0062] The other unstated parts are the same as the first embodiment, and will not be analyzed and described herein.

[0063] The third embodiment:

[0064] Referring to Figure 4 、 Figures 9-10 The hydraulic damper differs from the first embodiment in that:

[0065] The first piston 13 is provided with a fifth through hole 19 communicating with the first oil chamber 2, the second spring sheet 5 is provided with a seventh through hole 25 communicating with the fifth through hole 19, the second piston 14 is provided with a ramp 23 with a gradually changing height, the ramp 23 and the seventh through hole 25 leave a second gap 24 therebetween, the seventh through hole 25 communicates with the second oil chamber 3 through the second gap 24, the fifth through hole 19, the seventh through hole 25 and the second gap 24 constitute an intermediate flow channel, the first piston 13 and the second piston 14 rotate relative to each other to adjust the size of the second gap 24, and further adjust the size of the intermediate flow channel, and further change the flow speed of the damping oil and the size of the resistance, the larger the intermediate flow channel, the greater the damping oil flow rate, the smaller the damping force, the smaller the intermediate flow channel, the smaller the damping oil flow rate, the greater the damping force; the structure can realize stepless adjustment of the damping force.

[0066] The first spring sheet 4 is provided with a twelfth through hole 41, and the fifth through hole 19 communicates with the first oil chamber 2 through the twelfth through hole 41.

[0067] The other unstated parts are the same as the first embodiment, and will not be analyzed and described herein.

[0068] The above is the preferred scheme of the utility model, which shows and describes the basic principle, main features and advantages of the utility model. Those skilled in the art should understand that the utility model is not limited by the above embodiments, and the above embodiments and descriptions in the specification are only to illustrate the principle of the utility model, and various changes and improvements can be made without departing from the spirit and scope of the utility model, and these changes and improvements all fall within the scope of the utility model claimed. The scope of protection of the utility model is defined by the appended claims and their equivalents.

Claims

1. A hydraulic damper comprising a cylinder (1) and a damping assembly (A) telescopically arranged in the cylinder (1), the damping assembly (A) comprising a piston body separating an inner cavity (B) of the cylinder (1) into a first oil chamber (2) and a second oil chamber (3) in communication with each other, characterized in that: The piston body is provided with a first elastic sheet (4) and a second elastic sheet (5), the first elastic sheet (4) is located on the first oil cavity (2), the second elastic sheet (5) is located on the second oil cavity (3), a first channel (6) communicating the second oil cavity (3) is arranged between the piston body and the second elastic sheet (5), the first elastic sheet (4) closes the first channel (6), a second channel (7) communicating the first oil cavity (2) is arranged between the piston body and the first elastic sheet (4), the second elastic sheet (5) closes the second channel (7); When the damping assembly (A) is compressed with great force, the oil pressure of the second oil cavity (3) acts on the first elastic sheet (4) through the first channel (6), so that the first elastic sheet (4) is elastically deformed and the first channel (6) is opened, and the second oil cavity (3) is communicated with the first oil cavity (2) through the first channel (6); when the compression force of the damping assembly (A) decreases, the first elastic sheet (4) is elastically reset to close the first channel (6); When the damping assembly (A) is pulled out, the oil pressure of the first oil cavity (2) acts on the second elastic sheet (5) through the second channel (7), so that the second elastic sheet (5) is elastically deformed and the second channel (7) is opened, and the first oil cavity (2) is communicated with the second oil cavity (3) through the second channel (7); when the damping assembly (A) stops being pulled out, the second elastic sheet (5) is elastically reset to close the second channel (7).

2. Hydraulic damper according to claim 1, characterized in that The second oil cavity (3) is provided with a movable piston assembly, the movable piston assembly comprises a movable piston (8) and an elastic member (9), and the elastic member (9) is arranged between the movable piston (8) and the cylinder body (1); when the damping assembly (A) is pulled out, the movable piston (8) moves upward under the elastic force of the elastic member (9), and when the damping assembly (A) is compressed, the movable piston (8) is acted on to move downward and compress the elastic member (9), so that the damping oil in the second oil cavity (3) is always filled.

3. The hydraulic damper of claim 1, wherein: A first sealing ring (10) and a first gap (11) are arranged between the piston body and the cylinder body (1), the first gap (11) respectively communicates the first oil cavity (2) and the second oil cavity (3), the first sealing ring (10) is located in the middle of the first gap (11), and the inner side of the cylinder body (1) is provided with one or more oil passing grooves (12); the first sealing ring (10) moves up and down when the damping assembly (A) is stretched and contracted, when the first sealing ring (10) moves up and down to the position of the non-oil passing groove (12), the first sealing ring (10) closes the first gap (11), and when the first sealing ring (10) moves up and down to the position of the oil passing groove (12), the first oil cavity (2) is communicated with the second oil cavity (3) through the first gap (11) and the oil passing groove (12).

4. The hydraulic damper of claim 1, wherein: The piston body comprises a first piston (13) and a second piston (14) arranged in an upper and lower manner and relatively rotating, the first spring (4) is arranged on the top of the first piston (13), the second spring (5) is arranged between the first piston (13) and the second piston (14), the first piston (13) is provided with a first through hole (15) and a second through hole (16), the first spring (4) is provided with a third through hole (17), the second spring (5) is provided with a fourth through hole (18), the first through hole (15) is communicated with the fourth through hole (18) and forms a first channel (6), the fourth through hole (18) is communicated with the second oil cavity (3), the second through hole (16) is communicated with the third through hole (17) and forms a second channel (7), and the third through hole (17) is communicated with the first oil cavity (2).

5. Hydraulic damper according to claim 4, characterized in that: The first piston (13) is provided with a fifth through hole (19) communicated with the first oil cavity (2), the second piston (14) is provided with a sixth through hole (20) communicated with the second oil cavity (3), an intermediate flow channel is arranged between the first piston (13) and the second piston (14), the fifth through hole (19) is communicated with the sixth through hole (20) through the intermediate flow channel, and the length of the intermediate flow channel can be adjusted when the first piston (13) and the second piston (14) relatively rotate. The second piston (14) is provided with an arc-shaped flow channel (21), one end of the flow channel (21) is communicated with the sixth through hole (20), the fifth through hole (19) relatively slides along the flow channel (21) when the first piston (13) and the second piston (14) relatively rotate, and the part of the flow channel (21) through which the fifth through hole (19) and the sixth through hole (20) pass constitutes the intermediate flow channel.

6. The hydraulic damper of claim 4, wherein: The first piston (13) is annularly provided with a plurality of adjusting holes (22) with different diameters, the adjusting holes (22) are communicated with the first oil cavity (2), the second piston (14) is provided with the sixth through hole (20) communicated with the second oil cavity (3), the sixth through hole (20) and the adjusting hole (22) constitute the intermediate flow channel when they are communicated, and the first piston (13) and the second piston (14) relatively rotate to rotate to the position of different adjusting holes (22) through the sixth through hole (20) so as to adjust the size of the intermediate flow channel.

7. The hydraulic damper of claim 4, wherein: The first piston (13) is provided with the fifth through hole (19) communicated with the first oil cavity (2), the second spring (5) is provided with a seventh through hole (25) communicated with the fifth through hole (19), the second piston (14) is provided with a slope (23) with a gradually changing height, a second gap (24) is left between the slope (23) and the seventh through hole (25), the seventh through hole (25) is communicated with the second oil cavity (3) through the second gap (24), the fifth through hole (19), the seventh through hole (25) and the second gap (24) constitute the intermediate flow channel, the size of the second gap (24) is adjusted when the first piston (13) and the second piston (14) relatively rotate, and then the size of the intermediate flow channel is adjusted.

8. Hydraulic damper according to any of claims 5-7, characterized in that: The damping assembly (A) further comprises a piston shaft (26) penetrating through the first piston (13) and the second piston (14), the piston shaft (26) is fixedly connected with the second piston (14), the piston shaft (26) is rotationally matched with the first piston (13), and the piston shaft (26) drives the second piston (14) to rotate when rotating, so that the first piston (13) and the second piston (14) rotate relatively.

9. Hydraulic damper according to claim 8, characterized in that: The first piston (13) is non-circular in shape, the inner cavity (B) is non-circular in shape, the first piston (13) is fixed on the inner cavity (B), and the second piston (14) is circular in shape and rotationally arranged on the inner cavity (B).

10. Hydraulic damper according to claim 9, characterized in that: Further comprising a cover body (27) fixed on the top end of the cylinder body (1), the piston shaft (26) penetrates through the cover body (27) and extends out of the cylinder body (1), a sealing assembly is arranged below the cover body (27), the sealing assembly is sleeved on the piston shaft (26), and the piston body is limitingly movable up and down on the inner cavity (B).

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