A bidirectional gas spring

Abstract

This invention discloses a bidirectional hydropneumatic spring, belonging to the field of hydraulic machinery technology. It has an oil cavity I between the outer wall of the inner cylinder and the inner wall of the outer cylinder; an air cavity I communicating with the atmosphere between the outer wall of the piston rod and the inner wall of the inner cylinder; a first connecting member fixed to the left end of the outer cylinder; a first end cap fixed to the left end of the inner cylinder; and an air cavity II communicating with the atmosphere between the first end cap, the first connecting member, and the outer cylinder; a second end cap fixed to the left end of the piston rod; and an oil cavity II communicating with oil cavity I between the first end cap, the second end cap, and the inner wall of the inner cylinder; a floating piston coaxially slidingly fitted within the inner cavity of the piston rod; and an oil cavity III communicating with oil cavity II between the floating piston, the second end cap, and the inner wall of the piston rod; a second connecting member fixed to the right end of the piston rod; and a sealed air cavity between the second connecting member, the floating piston, and the inner wall of the piston rod. This hydropneumatic spring exhibits increased stiffness during both tension and compression.

Description

Technical Field

[0001] This invention belongs to the field of hydraulic machinery technology, and specifically relates to a bidirectional oil-gas spring. Background Technology

[0002] Gas springs are typical hydraulic energy storage components. They utilize the compression of high-pressure nitrogen gas in a sealed chamber to absorb impact energy for cushioning, while simultaneously employing internal throttling to extinguish vibrations. Gas springs exhibit very pronounced nonlinear stiffness and damping characteristics; their stiffness increases significantly with increasing compression, and their damping increases with increasing compression speed. Therefore, gas springs possess excellent end-effector cushioning characteristics. Due to their high energy storage ratio per unit area at the end, gas springs also possess good impact resistance. Compared to traditional elastic damping components, gas springs also offer advantages such as high integration and small weight.

[0003] Traditional gas springs have only one mechanical property: stiffness increases when transitioning from a balanced stable state to a compressed state, and stiffness decreases when transitioning from a balanced stable state to a stretched state. This cannot meet the requirements of certain special operating conditions. For example, under certain conditions, gas springs need to have the characteristic of increasing stiffness in both stretched and compressed states. Summary of the Invention

[0004] In view of this, the present invention provides a bidirectional gas spring, which solves the technical problem that traditional gas springs do not have the characteristic that their stiffness increases when transitioning from a state of equilibrium to a state of tension and compression.

[0005] The present invention adopts the following technical solution:

[0006] A bidirectional gas spring includes an outer cylinder, an inner cylinder, a piston rod, a first connector, a first end cap, a second end cap, a floating piston, and a second connector.

[0007] The inner cylinder is coaxially and slidably fitted inside the outer cylinder, and an oil cavity I is provided between the outer wall of the inner cylinder and the inner wall of the outer cylinder;

[0008] The piston rod has a hollow structure and is coaxially and slidably fitted inside the inner cylinder. There is an air cavity I between the outer wall of the piston rod and the inner wall of the inner cylinder, which is connected to the atmosphere. The piston rod can drive the inner cylinder to move to the right together.

[0009] The first connector is fixedly connected to the left end of the outer cylinder.

[0010] The first end cap is fixedly connected to the left end of the inner cylinder, and there is an air cavity II communicating with the atmosphere between the first end cap, the first connecting member and the outer cylinder;

[0011] The second end cap is fixedly connected to the left end of the piston rod, and there is an oil chamber II communicating with the oil chamber I between the first end cap, the second end cap and the inner wall of the inner cylinder;

[0012] The floating piston is coaxially slidably fitted into the inner cavity of the piston rod, and there is an oil cavity III communicating with the oil cavity II between the floating piston, the second end cap and the inner wall of the piston rod;

[0013] The second connector is fixed to the right end of the piston rod, and there is a sealed air cavity between the second connector, the floating piston and the inner wall of the piston rod.

[0014] Furthermore, the outer cylinder inner cavity includes, from left to right, a first outer cylinder inner cavity and a second outer cylinder inner cavity, wherein the diameter of the first outer cylinder inner cavity is larger than the diameter of the second outer cylinder inner cavity, forming a shoulder of the outer cylinder inner cavity;

[0015] The outer wall of the inner cylinder consists of a first inner cylinder outer wall and a second inner cylinder outer wall from left to right. The diameter of the first inner cylinder outer wall is larger than the diameter of the second inner cylinder outer wall, forming a shoulder on the outer wall of the inner cylinder. The inner cavity of the inner cylinder consists of a first inner cylinder cavity and a second inner cylinder cavity from left to right. The diameter of the first inner cylinder cavity is larger than the diameter of the second inner cylinder cavity, forming a shoulder on the inner cavity of the inner cylinder.

[0016] The piston rod outer wall includes a first piston rod outer wall and a second piston rod outer wall from left to right. The diameter of the first piston rod outer wall is larger than the diameter of the second piston rod outer wall, forming a piston rod outer wall shoulder.

[0017] The inner cavity of the first outer cylinder is slidably connected to the outer wall of the first inner cylinder, and the inner cavity of the second outer cylinder is slidably connected to the outer wall of the second inner cylinder. The oil cavity I is formed between the inner wall of the first outer cylinder, the outer wall of the second inner cylinder, the shoulder of the inner cylinder and the shoulder of the outer wall of the inner cylinder.

[0018] The outer wall of the first piston rod is slidably connected to the inner cavity of the first inner cylinder, and the outer wall of the second piston rod is slidably connected to the inner cavity of the second inner cylinder, forming the air cavity I between the inner wall of the first inner cylinder, the outer wall of the second piston rod, the shoulder of the inner cylinder, and the shoulder of the outer wall of the piston rod.

[0019] Furthermore, a damping hole is provided on the shoulder of the outer wall of the inner cylinder, and the oil chamber I and the oil chamber II are connected through the damping hole;

[0020] The second end cap is provided with a throttling orifice, and the oil chamber II and the oil chamber III are connected through the throttling orifice.

[0021] Furthermore, the second end cap is a rotary structure with a cavity, the rotary structure being coaxially fixed to the left end of the piston rod, and a normally open hole is provided on the side wall of the rotary structure.

[0022] Furthermore, an oil passage hole communicating with the oil chamber I is provided on the outer cylinder.

[0023] Furthermore, the number of oil passage holes is two;

[0024] One-way oil filling valve and pressure sensor are respectively installed in the two oil passages.

[0025] Furthermore, a vent I communicating with the air cavity II is provided on the first connector;

[0026] A vent II that communicates with the air cavity is provided on the second connector.

[0027] Furthermore, a dynamic seal and a guide band are provided between the inner cavity of the first outer cylinder and the mating surface of the outer wall of the first inner cylinder;

[0028] A dynamic seal, a dustproof ring, and a guide belt are provided between the inner cavity of the second outer cylinder and the mating surface of the outer wall of the second inner cylinder.

[0029] A dynamic seal and a guide band are provided between the outer wall of the first piston rod and the mating surface of the inner cavity of the first inner cylinder.

[0030] A dustproof ring and a guide belt are provided between the outer wall of the second piston rod and the mating surface of the inner cavity of the second inner cylinder.

[0031] A dynamic seal and a guide band are provided between the outer wall of the floating piston and the inner cavity mating surface of the piston rod;

[0032] A static seal is provided between the first connector and the mating surface of the inner cavity of the first outer cylinder;

[0033] A static seal is provided between the mating surfaces of the first end cap and the inner cavity of the first inner cylinder.

[0034] A static seal is provided between the second connector and the mating surface of the piston rod inner cavity.

[0035] Furthermore, the area of ​​the left end face of the piston rod is larger than the annular cross-sectional area of ​​the oil chamber I.

[0036] Furthermore, both the first connector and the second connector are hinges.

[0037] Beneficial effects:

[0038] 1. The inner cylinder is coaxially and slidably fitted inside the outer cylinder, with an oil cavity I between the outer wall of the inner cylinder and the inner wall of the outer cylinder; the piston rod is a hollow structure and is coaxially and slidably fitted inside the inner cylinder, with an air cavity I communicating with the atmosphere between the outer wall of the piston rod and the inner wall of the inner cylinder, and the piston rod can drive the inner cylinder to move to the right together; the first connecting piece is fixedly connected to the left end of the outer cylinder; the first end cap is fixedly connected to the left end of the inner cylinder, with an air cavity II communicating with the atmosphere between the first end cap, the first connecting piece, and the outer cylinder; the second end cap is fixedly connected to the left end of the piston rod, with an oil cavity II communicating with oil cavity I between the first end cap, the second end cap, and the inner wall of the inner cylinder; the floating piston is coaxially and slidably fitted inside the piston rod cavity, with an oil cavity III communicating with oil cavity II between the floating piston, the second end cap, and the inner wall of the piston rod; the second connecting piece is fixedly connected to the right end of the piston rod, with a sealed air cavity between the second connecting piece, the floating piston, and the inner wall of the piston rod.

[0039] Thus, the air pressure in air chambers I and II is equal to the external atmospheric pressure. High-pressure oil is injected into oil chambers I, II, and III, and high-pressure gas is injected into the air chambers, making the initial gas pressure in the air chambers Pgas0. Oil chambers I, II, and III are filled with hydraulic oil (i.e., the rod-side chamber of the outer cylinder and the rodless-side chamber of the inner cylinder are filled with hydraulic oil), with an initial pressure of Poil0. When the hydraulic spring is in equilibrium, Pgas0 = Poil0. In equilibrium, since the high-pressure gas pressure in the air chamber is equal to the pressure in the oil chamber, the hydraulic pressure causes a preload in the bidirectional hydraulic spring. When the piston rod is subjected to a load less than or equal to the preload, the piston rod maintains... In a balanced and stable state, the bidirectional gas spring is equivalent to rigidity. When the compressive force on the piston rod is greater than the preload, the piston rod moves to the left relative to the inner cylinder. The high-pressure oil in oil chamber II flows into oil chamber III and pushes the floating piston to compress the air chamber, increasing the stiffness in the relatively balanced and stable state. When the piston rod is subjected to a tensile load greater than the preload, the piston rod drives the inner cylinder to move to the right relative to the outer cylinder, causing the inner cylinder to squeeze the high-pressure oil in oil chamber I. The high-pressure oil in oil chamber I enters oil chamber III through oil chamber II and pushes the floating piston to compress the air chamber, increasing the stiffness in the relatively balanced and stable state. Therefore, the stiffness of this gas spring increases when transitioning from a balanced state to a tensile and compressed state. The elastic and velocity characteristics of this bidirectional gas spring only begin to function when the external force on the piston rod is greater than the preload, and it achieves a bidirectional characteristic of gradually increasing compressive and tensile stiffness through a single air chamber.

[0040] 2. An oil cavity I is formed between the inner wall of the first outer cylinder, the outer wall of the second inner cylinder, the shoulder of the outer cylinder and the shoulder of the outer wall of the inner cylinder, and an air cavity I is formed between the inner wall of the first inner cylinder, the outer wall of the second piston rod, the shoulder of the inner cylinder and the shoulder of the outer wall of the piston rod. The structure is simple and compact.

[0041] Moreover, when the gas spring is in the stretched state, the inner cylinder's inner cavity shoulder can fit with the piston rod's outer wall shoulder, thereby causing the piston rod to move the inner cylinder to the right until the inner cylinder's outer wall shoulder fits with the outer cylinder's inner cavity shoulder. At this time, the piston rod is in its longest extended state.

[0042] 3. A damping hole is provided on the shoulder of the outer wall of the inner cylinder. Oil chamber I and oil chamber II are connected through the damping hole. A throttling hole is provided on the second end cover. Oil chamber II and oil chamber III are connected through the throttling hole. Damping is generated when the oil passes through the damping hole and the throttling hole. The structure is simple and compact.

[0043] 4. The second end cap is a rotary structure with a cavity. The rotary structure is coaxially fixed to the left end of the piston rod, and a normally open hole is provided on the side wall of the rotary structure.

[0044] Thus, under the compressed state of the oil-gas spring, when the piston rod moves to the left relative to the inner cylinder and the second end cap at the left end of the piston rod is about to be in contact with the right end of the first end cap, the high-pressure oil outside the rotary structure cavity can maintain communication with the high-pressure oil inside the rotary structure cavity through the normally open hole. At this time, the high-pressure oil in oil chamber II can still flow smoothly into oil chamber III. In addition, at the instant when the second end cap at the left end of the piston rod is disengaged from the first end cap, the high-pressure oil outside the rotary structure cavity can also maintain communication with the high-pressure oil inside the rotary structure cavity through the normally open hole. At this time, the high-pressure oil in oil chamber III can still flow smoothly into the outside of the rotary structure cavity in oil chamber II, thus avoiding the sudden pressure change experienced by the piston rod under the above conditions.

[0045] 5. There are two oil passage holes on the outer cylinder. A one-way oil filling valve and a pressure sensor are installed in the two oil passage holes respectively, which can not only conveniently fill the oil chamber with oil, but also monitor the pressure of the high-pressure oil in the oil chamber in real time.

[0046] 6. A dustproof ring and a guide belt are provided between the outer wall of the second piston rod and the inner cavity of the second inner cylinder. The dustproof ring can prevent external impurities from entering the air cavity, and the guide belt can guide the movement of the piston rod. Moreover, since the guide belt and the dustproof ring do not isolate the air cavity I from the outside air, the air cavity I is kept in communication with the outside air. When the piston rod moves to the right, it can compress and discharge the air in the air cavity I, so that the shoulder of the piston rod outer wall can fit with the shoulder of the inner cavity of the inner cylinder. Thus, the piston rod can drive the inner cylinder to move to the right together. The structure is simple and compact. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the structure of the bidirectional gas spring provided by the present invention;

[0048] Figure 2 yes Figure 1 A schematic diagram of a bidirectional gas spring in its neutral position.

[0049] Figure 3 yes Figure 1 Schematic diagram of a bidirectional gas spring in its shortest state;

[0050] Figure 4 yes Figure 1 Schematic diagram of a bidirectional gas spring in its longest position;

[0051] Figure 5 yes Figure 1 A cross-sectional view along line A-A;

[0052] Figure 6 yes Figure 1 A schematic diagram comparing the pressure characteristic curves of the compression stroke and extension stroke of a bidirectional hydraulic spring;

[0053] Figure 7 yes Figure 1 Schematic diagram of the elastic characteristic curve of a bidirectional hydro-pneumatic spring during compression stroke;

[0054] Figure 8 yes Figure 1 Schematic diagram of the elastic characteristic curve of the tension stroke of a bidirectional hydraulic spring;

[0055] Figure 9 yes Figure 1 Schematic diagram of the compression stroke speed characteristic curve of a bidirectional hydropneumatic spring;

[0056] Figure 10 yes Figure 1 Schematic diagram of the speed characteristic curve of the extension stroke of a bidirectional hydraulic spring;

[0057] Wherein, 1 – First connecting piece; 2 – First lifting ring; 3 – Dust cover; 4 – External hexagonal screw I; 5 – Internal hexagonal screw I; 6 – First end cap; 7 – Inner cylinder; 8 – Dynamic seal I; 9 – Guide band I; 10 – Internal hexagonal screw II; 11 – Second end cap; 12 – Dynamic seal II; 13 – Guide band II; 14 – Outer cylinder; 15 – Guide band III; 16 – Piston rod; 17 – Dust ring I; 18 – Static seal I; 19 – External hexagonal screw II; 20 – One-way inflation valve; 21 – Second lifting ring; 22 – Second connecting piece; 23 – Static seal 24 - Guide band IV; 25 - Dynamic seal III; 26 - Dynamic seal IV; 27 - Dynamic seal V; 28 - Guide band V; 29 - Dust seal II; 30 - Vent I; 31 - Air chamber II; 32 - Oil chamber I; 33 - Damping orifice; 34 - Oil chamber II; 35 - Throttling orifice; 36 - Oil chamber III; 37 - Air chamber; 38 - Vent II; 39 - Normally open orifice; 40 - Static seal III; 41 - One-way oil filling valve; 42 - Oil passage I; 43 - Oil passage II; 44 - Floating piston; 45 - Air chamber I. Detailed Implementation

[0058] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. In the description of the present invention, it should be understood that directional terms such as "front," "back," "up," "down," "left," "right," "horizontal," "vertical," "horizontal," and "top," "bottom," etc., indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. These terms are used only for the convenience of describing the present invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the scope of protection of the present invention. The directional terms "inner" and "outer" refer to the inner or outer contours relative to the outline of each component itself.

[0059] Reference Figures 1-10 A bidirectional gas spring, comprising an outer cylinder, an inner cylinder, a piston rod, a first connecting member, a first end cap, a second end cap, a floating piston, and a second connecting member, wherein:

[0060] The inner cylinder 7 is coaxially slidably fitted inside the outer cylinder 14. An annular oil cavity I32 exists between the outer wall of the inner cylinder 7 and the inner wall of the outer cylinder 14. The piston rod 16 is hollow. The area of ​​the left end face of the piston rod 16 (i.e., the circular area corresponding to the diameter of the outer wall of the left end of the piston rod 16) can be equal to or unequal to the annular cross-sectional area of ​​the oil cavity I32 (in this embodiment, the area of ​​the left end face of the piston rod 16 is greater than the annular cross-sectional area of ​​the oil cavity I32). The piston rod 16 is coaxially slidably fitted inside the inner cylinder 7. An air cavity I45, communicating with the atmosphere, exists between the outer wall of the piston rod 16 and the inner wall of the inner cylinder 7. The piston rod 16 can drive the inner cylinder 7 to move to the right together. The right end of the first connecting piece 1 is connected to the left end of the outer cylinder 14 by multiple hexagonal screws I4 evenly distributed circumferentially. The first end cap 6 is connected to the left end of the inner cylinder 7. The piston rod 16 is connected by multiple hexagon socket head cap screws I5 evenly distributed around the circumference. An air cavity II31, which communicates with the atmosphere, is located between the first end cap 6, the first connecting piece 1, and the outer cylinder 14. The second end cap 11 is connected to the left end of the piston rod 16 by multiple hexagon socket head cap screws II10 evenly distributed around the circumference. An oil cavity II34, which communicates with the oil cavity I32, is located between the first end cap 6, the second end cap 11, and the inner wall of the inner cylinder 7. The floating piston 44 is coaxially and slidably fitted into the inner cavity of the piston rod 16. An oil cavity III36, which communicates with the oil cavity II34, is located between the floating piston 44, the second end cap 11, and the inner wall of the piston rod 16. The second connecting piece 22 is fixed to the right end of the piston rod 16. A sealed air cavity 37, which is used to contain high-pressure gas, is located between the second connecting piece 22, the floating piston 44, and the inner wall of the piston rod 16.

[0061] Thus, the air pressure in air chambers I45 and II31 is equal to the external atmospheric pressure. After high-pressure oil is filled into oil chambers I32, II34, and III36 (i.e., the rod-side chamber of the outer cylinder 14 and the rodless-side chamber of the inner cylinder 7 are filled with hydraulic oil), let the initial pressure be Poil0. After high-pressure gas is filled into air chamber 37, let the initial gas pressure in air chamber 37 be Pgas0. When the oil-gas spring is in equilibrium, Pgas0 = Poil0. The piston rod 16 has a preload in a balanced and stable state. When the piston rod 16 is subjected to a load less than or equal to the preload, the piston rod 16 remains in a balanced and stable state. When subjected to a compressive load greater than the preload, the piston rod 16 moves to the left relative to the inner cylinder 7. High-pressure oil in oil chamber II 34 flows into oil chamber III 36, pushing the floating piston 44 to compress the air chamber 37, increasing the stiffness in the relatively balanced and stable state. When the piston rod 16 is subjected to a tensile load greater than the preload, the piston rod 16 drives the inner cylinder 7 to move to the right relative to the outer cylinder 14, causing the inner cylinder 7 to squeeze the high-pressure oil in oil chamber I 32. The high-pressure oil in oil chamber I enters oil chamber III through oil chamber II, pushing the floating piston to compress the air chamber 37, increasing the stiffness in the relatively balanced and stable state. Therefore, the stiffness of this gas spring increases when transitioning from a balanced state to a tensile and compressed state. Furthermore, it can be understood that the stiffness in the compressed state is related to the area of ​​the left end face of the piston rod 16, while the stiffness in the tensile state is related to the annular cross-sectional area of ​​oil chamber I. In addition, the elastic and velocity characteristics of this bidirectional gas spring only begin to function when the external force on the piston rod 16 is greater than the preload, and the gradually increasing bidirectional characteristics of compression and tension are achieved through a single air chamber 37. Specifically, the inner cavity of the outer cylinder 14 includes, from left to right, a first outer cylinder inner cavity and a second outer cylinder inner cavity, with the diameter of the first outer cylinder inner cavity being larger than the diameter of the second outer cylinder inner cavity, forming a shoulder of the outer cylinder inner cavity; the outer wall of the inner cylinder 7 includes, from left to right, a first inner cylinder outer wall and a second inner cylinder outer wall, with the diameter of the first inner cylinder outer wall being larger than the diameter of the second inner cylinder outer wall, forming a shoulder of the inner cylinder outer wall; the inner cavity of the inner cylinder 7 includes, from left to right, a first inner cylinder inner cavity and a second inner cylinder inner cavity, with the diameter of the first inner cylinder inner cavity being larger than the diameter of the second inner cylinder inner cavity, forming a shoulder of the inner cylinder inner cavity.

[0062] It should also be noted that in this embodiment, the inner cavity of the first inner cylinder is divided into two sections, with the section closer to the first end cap 6 having a slightly larger diameter. During installation, the piston rod 16 is inserted from the larger-diameter end of the first inner cylinder cavity, allowing the piston rod 16 to slide into the other section of the first inner cylinder cavity. When inserting the piston rod 16, the larger-diameter end of the first inner cylinder cavity acts as a guide. Moreover, since the piston rod 16 does not slide into the guiding section, its machining precision can be lower than that of the other section that slides into the piston rod 16.

[0063] The outer wall of the piston rod 16 includes, from left to right, a first piston rod outer wall and a second piston rod outer wall. The diameter of the first piston rod outer wall is larger than that of the second piston rod outer wall, forming a shoulder on the piston rod outer wall.

[0064] The inner wall of the first outer cylinder is slidably connected to the outer wall of the first inner cylinder, and the inner wall of the second outer cylinder is slidably connected to the outer wall of the second inner cylinder, forming an oil cavity I32 between the inner wall of the first outer cylinder, the outer wall of the second inner cylinder, the shoulder of the inner cylinder, and the shoulder of the outer wall of the inner cylinder; the outer wall of the first piston rod is slidably connected to the inner wall of the first inner cylinder, and the outer wall of the second piston rod is slidably connected to the inner wall of the second inner cylinder, forming an air cavity I45 between the inner cavity of the first inner cylinder, the outer wall of the second piston rod, the shoulder of the inner cylinder, and the shoulder of the outer wall of the piston rod.

[0065] A dynamic seal I8 and a guide band I9 are provided between the mating surfaces of the inner cavity of the first outer cylinder and the outer wall of the first inner cylinder, which are slidably connected. A dynamic seal II12 and a guide band II13 are provided between the mating surfaces of the outer wall of the first piston rod and the inner cavity of the first inner cylinder, respectively. A guide band III15 and a dustproof ring I17 are provided between the mating surfaces of the outer wall of the second piston rod and the inner cavity of the second inner cylinder, respectively. A guide band IV24, a dynamic seal IV26, and a dustproof ring II29 are provided between the mating surfaces of the inner cavity of the second outer cylinder and the outer wall of the second inner cylinder, respectively. A dynamic seal III25 and a dynamic seal V27 are provided between the mating surfaces of the outer wall of the floating piston 44 and the inner cavity of the piston rod 16, respectively. A static seal I18 is provided between the outer wall of the second connecting member 22 and the mating surfaces of the inner cavity of the piston rod 16. Figure 1 As shown, the end of the first end cap 6 extends into the interior of the outer cylinder 14 and is provided with a static seal II23 between the mating surface of the first inner cylinder cavity and the end of the first connector 1 extends into the interior of the outer cylinder 14 and is provided with a static seal III40 between the mating surface of the first outer cylinder cavity and the mating surface of the first outer cylinder cavity.

[0066] In addition, multiple damping holes 33 are provided circumferentially at the shoulder of the inner cylinder 7. Oil chamber I32 and oil chamber II34 are connected through the damping holes 33. A throttling hole 35 is provided on the end face of the second end cover 11, and oil chamber II34 and oil chamber III36 are connected through the throttling hole 35. At least two oil passage holes communicating with oil chamber I32 are provided on the outer cylinder 14. In this embodiment, two oil passage holes are provided, namely oil passage hole I42 and oil passage hole II43. A pressure sensor is installed in oil passage hole I42. Figure 5(Not shown in the image) A one-way oil filling valve 41 is installed inside the oil passage II43. A vent I30 communicating with the air chamber II31 is provided on the first connecting member 1, and a dust cover is installed inside the vent I30 to prevent external debris from entering the air chamber II31. A vent II38 is provided on the second connecting member 22, and a one-way air filling valve 20 is installed inside the vent II38 to fill the air chamber 37 with high-pressure gas. Since the guide belt III15 and the dust cover II17 do not isolate the air chamber I from the outside air, the air chamber I45 can remain connected to the outside atmosphere. Of course, a through hole can also be provided at a suitable position on the outer wall of the inner cylinder 7 to allow the air chamber I45 to remain connected to the outside atmosphere.

[0067] The aforementioned first connecting member 1 and second connecting member 22 can be hinges or flanges, etc., and their structural forms can be flexibly designed according to the working conditions. In this embodiment, both the first connecting member 1 and the second connecting member 22 are hinges, and bearing holes and retaining ring grooves are machined on the hinges for installing bearing kits. A first lifting ring 2 is installed on the first connecting member 1 through a lifting ring threaded hole, and a second lifting ring 21 is installed on the second connecting member 22 through a lifting ring threaded hole for lifting and transportation. Moreover, in this embodiment, oil chambers I32, II34, and III36 are filled with high-pressure oil, and air chamber 37 is filled with high-pressure nitrogen. When the oil-air spring is in a balanced state, the pressure in air chamber 37 is equal to the oil pressure in oil chambers I32, II34, and III36.

[0068] More specifically, in this embodiment, the second end cap 11 is a rotary structure with a cavity. The rotary structure is coaxially connected to the left end of the piston rod 16. The throttle orifice 35 is disposed on the end face of the rotary structure near the floating piston 44. Specifically, it includes a ring of evenly arranged throttle orifices 35 and a throttle orifice 35 located on the axis of the rotary structure. Furthermore, a normally open hole 39 is provided on the side wall of the rotary structure. Thus, when the piston rod 16 of the gas spring is in a compressed state, that is, when the piston rod 16 moves to the left relative to the inner cylinder 7 and the second end cap 11 at the left end of the piston rod 16 is about to be in contact with the right end of the first end cap 6, the high-pressure oil outside the cavity of the rotary structure can maintain communication with the high-pressure oil inside the cavity of the rotary structure through the normally open hole 39. At this time, the high-pressure oil in the oil chamber II 34 can still flow smoothly into the oil chamber III 36. In addition, at the instant when the second end cap 11 at the left end of the piston rod 16 is disengaged from the first end cap 6, the high-pressure oil outside the cavity of the rotary structure can also maintain communication with the high-pressure oil inside the cavity of the rotary structure through the normally open hole. At this time, the high-pressure oil in the oil chamber III 36 can still flow smoothly into the outside of the cavity of the rotary structure in the oil chamber II 34, thus avoiding the sudden pressure change experienced by the piston rod 16 in the above instantaneous state.

[0069] This bidirectional gas spring has three extreme states depending on the position of the piston rod 16: the neutral state, the shortest state, and the longest state. Details are as follows:

[0070] (a) Median status

[0071] like Figure 2 As shown, the bidirectional hydropneumatic spring is in the neutral position when it is in a balanced and stable state (i.e., in the initial position). At this time, under the action of high-pressure oil and gas, the left end face of the first end cover 6 is in contact with the right end face of the first connecting piece 1, the shoulder of the piston rod outer wall is in contact with the shoulder end face of the inner cylinder, the air chamber I45 is completely compressed, the air in the air chamber I45 is leaked to the atmosphere, the left end face of the floating piston 44 is separated from the right end face of the second end cover 11 by a certain distance, the high-pressure nitrogen in the air chamber 37 provides preload for the neutral position, and the volume of the oil chamber I32 and the oil chamber II34 reaches the maximum.

[0072] (ii) Shortest state

[0073] like Figure 3 As shown, relative to the neutral position, the piston rod 16 is compressed, the outer wall shoulder of the piston rod is no longer in contact with the inner cylinder cavity shoulder end face, the left end face of the second end cover 11 is in contact with the right end face of the first end cover 6, and the volume of the oil cavity I32 and the air cavity I45 reaches its maximum.

[0074] (III) Longest State

[0075] like Figure 4 As shown, with the piston rod 16 extended relative to the neutral position, the shoulder of the outer cylinder cavity is in contact with the end face of the shoulder of the inner cylinder outer wall, and the shoulder of the piston rod outer wall is in contact with the end face of the shoulder of the inner cylinder cavity, and the oil chamber I32 and the air chamber I45 are completely compressed.

[0076] The following describes two operating conditions for this two-way gas spring:

[0077] Operating Condition 1: From the middle state to the longest state

[0078] Under this condition, the end face of the piston rod outer wall shoulder fits with the inner cylinder inner cavity shoulder, and the piston rod 16 and the inner cylinder 7 can be regarded as rigidly connected. The oil volume in oil chamber II 34 remains constant, and the change in oil volume in oil chamber I 32 is the same as the change in oil volume in oil chamber III 36. That is, when the transition from the intermediate state to the longest state, the floating piston 44 moves to the right relative to the piston rod 16, and the high-pressure gas in the gas chamber 37 is compressed, and the stiffness gradually increases. Conversely, the opposite is true when the transition from the longest state to the intermediate state.

[0079] Operating Condition 2: From Midpoint State to Shortest State

[0080] Under this condition, the left end face of the first end cap 6 is in contact with the right end face of the first connector 1. The two parts, the first end cap 6 and the first connector 1, can be regarded as a rigid connection. The volume of oil in the oil chamber I 32 remains constant. The change in the volume of oil in the oil chamber II 34 is the same as the change in the volume of oil in the oil chamber III 36. When the transition from the intermediate state to the shortest state occurs, the floating piston 44 moves to the right relative to the piston rod 16. The high-pressure gas in the gas chamber 37 is compressed and its stiffness gradually increases. Conversely, the opposite occurs when the transition from the shortest state to the intermediate state.

[0081] When the bidirectional gas spring is in equilibrium after installation, it is in its neutral state. As the gas spring transitions from the neutral state to its longest or shortest state, its elastic stiffness gradually increases. That is, the neutral state is the position where the bidirectional gas spring has the minimum stiffness. In the neutral state, since the high-pressure nitrogen pressure in the gas chamber 37 is equal to the pressure in the oil chamber, the bidirectional gas spring has a preload under the action of the oil pressure. When the load on the piston rod 16 is less than or equal to the set preload, the piston rod 16 of the bidirectional gas spring remains stationary. When the load is greater than the set preload, the piston rod 16 extends or is compressed.

[0082] Qualitatively speaking, in the bidirectional pneumatic spring from its neutral to its longest position, high-pressure oil enters oil chamber III34 from oil chamber I32, and the equivalent area of ​​the reaction force from the high-pressure oil is the annular cross-sectional area of ​​oil chamber I32. In the neutral to its shortest position, high-pressure oil enters oil chamber III36 from oil chamber II34, and the equivalent area of ​​the reaction force from the high-pressure oil is the circular cross-sectional area of ​​the outer wall of the first piston rod. Because the relationship between the pressure in air chamber 37 and the displacement of floating piston 44 is constant, the amount of oil entering oil chamber III36 is positively correlated with the annular cross-sectional area of ​​oil chamber I32, and the amount of oil entering oil chamber III36 is also positively correlated with the circular cross-sectional area of ​​the outer wall of the first piston rod (i.e., the circular area corresponding to the diameter of the outer wall of the left end of piston rod 16). Quantitatively speaking, let the annular cross-sectional area of ​​oil chamber I32 be Ah, the circular cross-sectional area of ​​the outer wall of the first piston rod be Az, the cross-sectional area of ​​the floating piston be Aq (i.e., the cross-sectional area of ​​the inner cavity of piston rod 16), and the displacement of the floating piston 44 be S. According to the fluid continuity theorem, the volume change of gas chamber 37 during compression is V. 压缩 =Az·S, the change in volume of air cavity 37 during the stretching process is V 压缩=Ah·S, and according to the ideal gas law PV=nRT, since the right side of the equation is a constant, the pressure of the gas chamber 37 is related to its volume change. Furthermore, because the volume change of the gas chamber 37 during compression and extension processes is directly related to the annular cross-sectional area Ah of the oil chamber I32 and the circular cross-sectional area Az of the outer wall of the first piston rod, the characteristics of this bidirectional hydraulic spring are directly related to the annular cross-sectional area Ah of the oil chamber I32 and the circular cross-sectional area Az of the outer wall of the first piston rod. This is the essence of the compression and extension characteristics of the bidirectional hydraulic spring. In this embodiment, the pressure characteristics and elastic characteristics of the bidirectional hydraulic spring are as follows: Figures 6 to 8 As shown. During compression, the oil in this bidirectional gas spring only passes through the throttle orifice 35, and most of the damping is generated by the throttle orifice 35. During extension, the oil needs to flow through both the damping orifice 33 and the throttle orifice 35. The difference in compression and extension speed characteristics can be achieved through the matching design of the damping orifice 33 and the throttle orifice 35. In this embodiment, the compression and extension speed characteristics of the bidirectional gas spring are as follows: Figure 9 and Figure 10 As shown.

[0083] In summary, the above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A bidirectional gas spring, characterized in that, It includes an outer cylinder, an inner cylinder, a piston rod, a first connecting member, a first end cap, a second end cap, a floating piston, and a second connecting member; The inner cylinder is coaxially and slidably fitted inside the outer cylinder, and an oil cavity I is provided between the outer wall of the inner cylinder and the inner wall of the outer cylinder; The piston rod has a hollow structure and is coaxially and slidably fitted inside the inner cylinder. There is an air cavity I between the outer wall of the piston rod and the inner wall of the inner cylinder, which is connected to the atmosphere. The piston rod can drive the inner cylinder to move to the right together. The first connector is fixedly connected to the left end of the outer cylinder. The first end cap is fixedly connected to the left end of the inner cylinder, and there is an air cavity II communicating with the atmosphere between the first end cap, the first connecting member and the outer cylinder; The second end cap is fixedly connected to the left end of the piston rod, and there is an oil chamber II communicating with the oil chamber I between the first end cap, the second end cap and the inner wall of the inner cylinder; The floating piston is coaxially slidably fitted into the inner cavity of the piston rod, and there is an oil cavity III communicating with the oil cavity II between the floating piston, the second end cap and the inner wall of the piston rod; The second connector is fixed to the right end of the piston rod, and there is a sealed air cavity between the second connector, the floating piston and the inner wall of the piston rod.

2. The bidirectional gas spring according to claim 1, characterized in that, The outer cylinder inner cavity includes, from left to right, a first outer cylinder inner cavity and a second outer cylinder inner cavity. The diameter of the first outer cylinder inner cavity is larger than the diameter of the second outer cylinder inner cavity, forming a shoulder of the outer cylinder inner cavity. The outer wall of the inner cylinder consists of a first inner cylinder outer wall and a second inner cylinder outer wall from left to right. The diameter of the first inner cylinder outer wall is larger than the diameter of the second inner cylinder outer wall, forming a shoulder on the outer wall of the inner cylinder. The inner cavity of the inner cylinder consists of a first inner cylinder cavity and a second inner cylinder cavity from left to right. The diameter of the first inner cylinder cavity is larger than the diameter of the second inner cylinder cavity, forming a shoulder on the inner cavity of the inner cylinder. The piston rod outer wall includes a first piston rod outer wall and a second piston rod outer wall from left to right. The diameter of the first piston rod outer wall is larger than the diameter of the second piston rod outer wall, forming a piston rod outer wall shoulder. The inner cavity of the first outer cylinder is slidably connected to the outer wall of the first inner cylinder, and the inner cavity of the second outer cylinder is slidably connected to the outer wall of the second inner cylinder. The oil cavity I is formed between the inner wall of the first outer cylinder, the outer wall of the second inner cylinder, the shoulder of the inner cylinder and the shoulder of the outer wall of the inner cylinder. The outer wall of the first piston rod is slidably connected to the inner cavity of the first inner cylinder, and the outer wall of the second piston rod is slidably connected to the inner cavity of the second inner cylinder, forming the air cavity I between the inner wall of the first inner cylinder, the outer wall of the second piston rod, the shoulder of the inner cylinder, and the shoulder of the outer wall of the piston rod.

3. A bidirectional gas spring according to claim 2, characterized in that, A damping hole is provided on the shoulder of the outer wall of the inner cylinder, and the oil chamber I and the oil chamber II are connected through the damping hole; The second end cap is provided with a throttling orifice, and the oil chamber II and the oil chamber III are connected through the throttling orifice.

4. A bidirectional gas spring according to claim 3, characterized in that, The second end cap is a rotary structure with a cavity. The rotary structure is coaxially fixed to the left end of the piston rod, and a normally open hole is provided on the side wall of the rotary structure.

5. A bidirectional gas spring according to claim 1, characterized in that, An oil passage hole communicating with the oil chamber I is provided on the outer cylinder.

6. A bidirectional gas spring according to claim 5, characterized in that, There are two oil passage holes; One-way oil filling valve and pressure sensor are respectively installed in the two oil passages.

7. A bidirectional gas spring according to claim 1, characterized in that, A vent I communicating with the air cavity II is provided on the first connector; A vent II that communicates with the air cavity is provided on the second connector.

8. A bidirectional gas spring according to any one of claims 2 to 4, characterized in that, A dynamic seal and a guide strip are provided between the inner cavity of the first outer cylinder and the mating surface of the outer wall of the first inner cylinder; A dynamic seal, a dustproof ring, and a guide belt are provided between the inner cavity of the second outer cylinder and the mating surface of the outer wall of the second inner cylinder. A dynamic seal and a guide band are provided between the outer wall of the first piston rod and the mating surface of the inner cavity of the first inner cylinder. A dustproof ring and a guide belt are provided between the outer wall of the second piston rod and the mating surface of the inner cavity of the second inner cylinder. A dynamic seal and a guide band are provided between the outer wall of the floating piston and the inner cavity mating surface of the piston rod; A static seal is provided between the first connector and the mating surface of the inner cavity of the first outer cylinder; A static seal is provided between the mating surfaces of the first end cap and the inner cavity of the first inner cylinder. A static seal is provided between the second connector and the mating surface of the piston rod inner cavity.

9. A bidirectional gas spring according to any one of claims 1 to 7, characterized in that, The area of ​​the left end face of the piston rod is larger than the annular cross-sectional area of ​​the oil chamber I.

10. A bidirectional gas spring according to any one of claims 1 to 7, characterized in that, Both the first connector and the second connector are hinges.

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