Air spring

Abstract

The utility model belongs to the technical field of automobile suspensions, and particularly relates to an air spring which comprises a base, an air bag and a piston which are arranged from bottom to top, and an air containing cavity is defined by the base, the air bag and the piston. The piston is provided with a column cavity with a downward opening, a plunger in axial sliding sealing fit with the inner side wall of the piston is arranged in the column cavity, and the lower end of the plunger is connected to the base. The plunger divides the gas containing cavity into a main gas chamber and a compressed gas chamber, and the compressed gas chamber is located on the upper side of the top face of the plunger. The piston is provided with a first inflation inlet communicated with the main air chamber, a second inflation inlet communicated with the compression air chamber and an air outlet. And a one-way valve leading to the compressed air chamber is arranged on the second inflation port. Vehicle kinetic energy absorbed by the air spring is converted into telescopic motion of the plunger, power is provided for extracting gas from the compression gas chamber, compressing the gas in the compression gas chamber and conveying high-pressure gas out of the compression gas chamber, the high-pressure gas used by other devices is generated, and environment friendliness is achieved. Heat of the air spring is reduced, and service life of the air spring is prolonged.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the technical field of automobile suspension, concretely relates to an air spring. BACKGROUND

[0002] Air spring is a kind of spring using compressed air as elastic medium, its working principle is to fill compressed air in sealed air bag, and elasticity is realized by using the compressibility of air, and air spring absorbs the kinetic energy of vehicle body and realizes the vibration isolation and buffering of vehicle body by compression movement, to ensure the ride comfort of vehicle.

[0003] The existing air spring mainly includes base, air bag and piston, the lower end of air bag is sealingly matched with base, the upper end of air bag is sealingly matched with the lower end of piston, and base, air bag and piston enclose closed gas chamber.Base is connected on wheel frame, and piston is connected on suspension, and the stiffness of air spring is adjusted by filling gas chamber in air bag through air pump to meet the driving demand of vehicle on different road conditions, to improve the ride comfort of vehicle.The kinetic energy absorbed by air spring is converted into heat energy in the process of vibration of vehicle, and is discharged to air, to cause energy waste.In addition, the high temperature of air spring in the process of heat dissipation of air spring can accelerate the aging of air spring rubber material air bag, to shorten the service life of air spring. UTILITY MODEL CONTENTS

[0004] The utility model provides a kind of air spring, utilize the compression force of compressed gas that its own telescopic movement is converted to the kinetic energy generated by vehicle body vibration, energy saving and environmental protection, reduce air spring heat output, prolong the service life of air spring.

[0005] The utility model solves the technical scheme that the technical problem employing is as follows: a kind of air spring, including base, air bag and piston, the lower end of the base sealing air bag, the upper end of the piston sealing air bag, the base, the air bag and the piston enclose closed gas cavity;

[0006] The piston has opening downward column cavity, the column cavity is equipped with the plunger that is axially slidingly matched with the inner side wall of the piston, the plunger is sealingly matched with the inner side wall of the piston, and the lower end of the plunger is connected to the base;The plunger separates the gas cavity into main gas chamber and compression gas chamber isolated from each other, and the compression gas chamber is located on the upper side of the plunger top surface;

[0007] The piston is equipped with the first inflation port that is communicated with the main gas chamber, the second inflation port that is communicated with the compression gas chamber and the gas outlet that is communicated with the compression gas chamber;One-way valve leading to the compression gas chamber is provided on the second inflation port.

[0008] Further, the lower end of the piston is provided with an axial limiting part protruding inwardly from the inner side wall of the piston.

[0009] Further, the axial limiting part is a ring plate structure integrally formed with the piston, and the axial limiting part of the ring plate structure is coaxially arranged with the piston.

[0010] The piston comprises a piston cylinder with two open ends and a top plate welded on the upper part of the piston cylinder, the top plate seals the upper port of the piston cylinder, and the top plate and the inner wall of the piston cylinder form a column cavity of the piston; the plunger is detachably connected with the base.

[0011] Further, a limiting step is arranged on the inner side wall of the upper part of the piston cylinder, and the top plate is located in the piston cylinder and the lower end surface of the top plate is in close contact with the top surface of the limiting step.

[0012] Further, the second air inlet is arranged on the top plate, and the second air inlet is covered with filter cotton.

[0013] The upper surface of the filter cotton is located below the upper end surface of the piston cylinder.

[0014] Further, a buffer limiting part is arranged in the compression gas chamber, and the buffer limiting part is located between the plunger and the top plate.

[0015] Further, the one-way valve comprises a guide rod, an axial limiting plate and a one-way valve piece arranged in the compression gas chamber.

[0016] The guide rod is parallel to the axis of the plunger, the upper end of the guide rod is connected to the top plate, the axial limiting plate is fixedly installed at the lower end of the guide rod and is arranged in spaced relation to the top plate, the one-way valve piece is arranged between the axial limiting plate and the top plate, the one-way valve piece is installed on the guide rod and axially slides with the guide rod.

[0017] Further, the plunger comprises a plunger body, an annular groove coaxial with the plunger body is arranged on the outer side surface of the plunger body, a first sealing ring is arranged in the annular groove, and the first sealing ring protrudes from the outer side surface of the plunger body and sealingly cooperates with the inner side wall of the piston.

[0018] An annular part integrally formed with the first sealing ring and protruding upwardly from the upper end surface of the plunger body is arranged on the first sealing ring, and the annular part is the buffer limiting part.

[0019] Further, a connecting rod is arranged in the main gas chamber, the upper end of the connecting rod is hingedly connected with the plunger through a universal ball head, and the lower end of the connecting rod is detachably connected with the base.

[0020] Further, the base is provided with an axial through limiting step hole, and a large hole of the limiting step hole is located close to one side of the main air chamber;

[0021] The lower part of the connecting rod is provided with a shaft ring integrally formed therewith, the upper clamp of the connecting rod below the shaft ring is provided with a second sealing ring, and the upper part of the connecting rod below the second sealing ring is provided with a threaded section; the second sealing ring is in sealing cooperation with the connecting rod;

[0022] The connecting rod penetrates through the limiting step hole, the second sealing ring is in sealing cooperation with the hole wall of the large hole of the limiting step hole, the shaft ring is in axial abutment with the top surface of the base, and the threaded section protrudes downward from the base and is connected with a fastening nut, and the upper end surface of the fastening nut is closely combined with the base.

[0023] Compared with the prior art, the air spring has the advantages that: a compression gas chamber with adjustable volume is formed by arranging a plunger forming body in axial sliding cooperation with the side wall of the piston column cavity, the vehicle kinetic energy absorbed by the air spring drives the plunger to extend and retract to change the volume of the compression gas chamber, and the opening and closing of the second inflation port are controlled by arranging a one-way valve on the second inflation port in communication with the compression gas chamber. That is, the air pressure in the compression gas chamber is less than the external atmospheric pressure during the stretching movement of the air spring, the one-way valve opens the second inflation port; when the air spring is compressed, the air pressure in the compression gas chamber is greater than the external atmospheric pressure, the one-way valve closes the second inflation port and compresses the gas in the compression gas chamber into high-pressure gas, the high-pressure gas generated by the compression movement of the air spring is discharged from the gas outlet to other devices for application, and the air spring is green and environmentally friendly. In addition, the kinetic energy of the vehicle absorbed by the air spring is converted into the extension and retraction movement of the plunger, and finally converted into the power for extracting gas from the compression gas chamber, compressing and pressurizing the gas in the compression gas chamber, and delivering high-pressure gas outside the compression gas chamber, thereby reducing the generation of heat of the air spring, slowing down the aging of the air bag, and prolonging the service life of the air spring. The plunger is axially limited by the axial limiting part arranged at the lower end of the piston, so that the plunger is prevented from coming out of the column cavity of the piston, the installation of the plunger is facilitated, and the reliability of the air spring is improved. The plunger and the piston can be deflected by a certain angle relative to the base by arranging the push rod hinged with the plunger through the universal ball head to adapt to the deflection of the base and the piston during the extension and retraction movement of the air spring. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 It is an axial sectional view of the utility model;

[0025] Figure 2 It is Figure 1 It is an enlarged structure schematic view of part A in the utility model;

[0026] Figure 3 It is Figure 1 It is an enlarged structure schematic view of part B in the utility model;

[0027] Figure 4 is Figure 1 is an enlarged structural schematic view of the C part in the middle;

[0028] Figure 5 is an axial sectional structural schematic view of the base;

[0029] Figure 6 is an assembled structural schematic view of the connecting rod and the plunger;

[0030] Reference signs: 1 - base; 11 - annular part; 12 - mounting cavity; 2 - air bag; 3 - plunger; 31 - first inflation port; 32 - second inflation port; 33 - air outlet; 34 - axial limiting part; 35 - plunger cylinder; 36 - top plate; 37 - limiting step; 38 - filter cotton; 41 - main gas chamber; 42 - compressed gas chamber; 43 - buffer limiting part; 5 - plunger; 51 - plunger body; 52 - first sealing ring; 6 - connecting rod; 61 - shaft ring; 62 - second sealing ring; 63 - threaded section; 64 - fastening nut; 7 - one-way valve; 71 - guide rod; 72 - axial limiting plate; 73 - one-way valve piece. DETAILED DESCRIPTION

[0031] The utility model will be further explained in connection with the drawings and examples. The examples described below by referring to the drawings are exemplary, only for explaining the utility model, and cannot be understood as limiting the utility model.

[0032] As shown in the drawings, Figures 1-6 An air spring includes a base 1, an air bag 2 and a plunger 3, the base 1 seals the lower port of the air bag 2, the plunger 3 seals the upper port of the air bag 2, and the base 1, the air bag 2 and the plunger 3 enclose a closed gas cavity; the plunger 3 has a column cavity with an opening downward, the column cavity is provided with a plunger 5 in axial sliding fit with the inner side wall of the plunger 3, the plunger 5 is in sealing fit with the inner side wall of the plunger 3, and the lower end of the plunger 5 is connected to the base 1; the plunger 5 divides the gas cavity into a main gas chamber 41 and a compressed gas chamber 42 which are isolated from each other, and the compressed gas chamber 42 is located on the upper side of the top surface of the plunger 5; the plunger 3 is provided with a first inflation port 31 in communication with the main gas chamber 41, a second inflation port 32 in communication with the compressed gas chamber 42 and an air outlet 33 in communication with the compressed gas chamber 42; the second inflation port 32 is provided with a one-way valve 7 leading to the compressed gas chamber 42. The other gas cavities except the compressed gas chamber 42 are main gas chambers 41. The one-way valve 7 is used for controlling the opening and closing of the second inflation port 32.

[0033] The base 1 of the air spring is connected to a wheel frame, the piston 3 is connected to a suspension, and compressed gas is filled into the main air chamber 41 through the first air inlet 31 to meet the stiffness requirements of the vehicle. When the vehicle runs on uneven road surfaces, the body and the suspension drive the entire air spring to extend and contract, so that the base 1 and the piston 3 move relative to each other in the up-down direction. When the air spring is stretched, the base 1 and the piston 3 move away from each other, and the base 1 drives the plunger 5 to move downward relative to the piston 3, the plunger 5 slides downward in the column cavity of the piston 3 to gradually increase the volume of the compression chamber 42, and then the air pressure in the compression chamber 42 is lower than the atmospheric pressure outside, under the action of the air pressure difference, the one-way valve 7 is opened at the same time as the control of the second air inlet 32 is opened, and the external gas enters the compression chamber 42 through the second air inlet 32; when the air spring is compressed, the base 1 and the piston 3 move closer to each other, and the base 1 drives the plunger 5 to move upward relative to the piston 3, the plunger 5 slides upward in the column cavity of the piston 3 to gradually press the volume of the compression chamber 42 and the gas inside, the gas pressure of the compression chamber 42 gradually increases, and then the air pressure in the compression chamber 42 is higher than the air pressure of the external gas, under the action of the high-pressure gas in the compression chamber 42, the one-way valve 7 is closed and the second air inlet 32 is closed, and the high-pressure gas in the compression chamber 42 is discharged through the air outlet 33 to other devices for application, energy saving and environmental protection. The kinetic energy of the vehicle absorbed by the air spring is converted into the extension and contraction of the plunger 5, and finally converted into the power of extracting gas into the compression chamber 42, pressurizing the gas in the compression chamber 42 and delivering high-pressure gas outside the compression chamber 42, reducing the generation of heat of the air spring, slowing down the aging of the air bag and prolonging the service life of the air spring.

[0034] The base 1 is used for sealing the lower port of the air bag 2 and connecting the air spring to the wheel frame, and the base 1 can be a cylindrical structure with one end sealed or a solid columnar structure. The piston 3 is used for sealing the upper port of the air bag 2 and connecting the air spring to the vehicle suspension. The air bag 2 is generally sleeved on the outer circumferential surface of the base 1 and the piston 3, and the air bag 2 can be sealingly matched with the base 1 and sealingly matched with the piston 3 through hoop connection, pressure connection and the like. The piston 3 can be an integral structure integrally formed or a combined structure assembled by a plate and a sleeve. The main air chamber 41 is used for containing compressed gas, and the stiffness of the entire air spring is adjusted by adjusting the pressure of the compressed gas in the main air chamber 41 of the air spring. The vehicle air pump fills air into the main air chamber 41 through the first air inlet 31, and the first air inlet 31 can be arranged on the outer side wall or the top wall of the piston 3 and communicated with the main air chamber 41 through the air channel on the piston 3.

[0035] When the air spring stretching movement stroke is too large, the plunger 5 is easily slipped out of the lower port of the piston 3 and difficult to reset, resulting in air spring failure. Preferably, the lower end of the piston 3 is provided with an axial limiting portion 34 protruding inwardly from the inner side wall of the piston 3. The axial limiting portion 34 axially limits the plunger 5 in the column cavity of the piston 3, avoiding the plunger 5 from being pulled out, and improving the reliability of the air spring. After the air spring is installed on the vehicle, a limiting portion is provided on the vehicle suspension to prevent the plunger 5 from colliding with the axial limiting portion 34.

[0036] The axial limiting portion 34 can be a plurality of protruding portions distributed circumferentially along the piston 3, or can be a ring plate structure which can be fastened to the piston 3 by bolts, pins or other connecting members, or can be an integral structure integrally formed with the piston 3. As a further preferred, the axial limiting portion 34 is a ring plate structure integrally formed with the piston 3, and the axial limiting portion 34 of the ring plate structure is coaxially arranged with the piston 3. The reliability of the axial limiting portion 34 is improved, the structure is simple and convenient to process. The piston 3 and the axial limiting portion 34 are integrally formed, and the axial limiting portion 34 cannot be detached, so that the plunger 5 cannot be loaded into the column cavity from the lower port of the piston 3. Therefore, the piston 3 includes a piston barrel 35 with two open ends and a top plate 36 welded to the upper part of the piston barrel 35, the top plate 36 seals the upper port of the piston barrel 35, and the top plate 36 and the piston barrel 35 form the column cavity of the piston 3; the plunger 5 is detachably connected with the base 1. When assembling the air spring, the plunger 5 is first loaded into the column cavity from the upper port of the piston 3, then the plunger 5 is installed on the base 1 after being pulled out from the lower port of the piston 3, and finally the top plate 35 is sealed and welded on the piston 3.

[0037] The top plate 36 can be welded on the outside of the piston barrel 35, or can be welded on the inside of the piston barrel 35. Preferably, a limiting step 37 is provided on the inner side wall of the upper part of the piston barrel 35, and the top plate 36 is located in the piston barrel 35 and the lower end surface of the top plate 36 is in contact with the top surface of the limiting step 37. The limiting step 37 supports the top plate 36 to limit it in the axial direction of the piston 3, improves the assembly accuracy of the top plate 36, and reduces the volume deviation of the column cavity of the piston 3 and the compression chamber 42.

[0038] The second air inlet 32 is an air inlet passage of the compression gas chamber 42, and the air outlet 33 is an air outlet passage of the compression gas chamber 42. The second air inlet 32 is always located above the upper limit position of the plunger 5. Specifically, the second air inlet 32 is arranged on the top plate 36. The second air inlet 32 can be a round hole, a square hole, a ring-shaped hole or the like. Preferably, the second air inlet 32 is covered with filter cotton 38 to prevent dust outside the air spring from entering the compression gas chamber 42. The filter cotton 38 can be bonded to the top plate 36 or fixed to the top plate 36 by using an anchor, a bolt or the like. The upper surface of the filter cotton 38 is located below the upper end surface of the plunger cylinder 35 to prevent the filter cotton 38 from being covered by other structures and ensure that the second air inlet 32 is unobstructed when opened.

[0039] The one-way valve 7 on the second inflation port 32 is used to control the opening and closing of the second inflation port 32, that is, the one-way valve 7 opens the second inflation port 32 when the plunger 5 moves downward, and closes the second inflation port 32 when the plunger 5 moves upward. Specifically, the one-way valve 7 includes a guide rod 71, an axial limiting plate 72, and a one-way valve plate 73 arranged in the compression chamber 42; the guide rod 71 is parallel to the axis of the plunger 5, and the upper end of the guide rod 71 is connected to the top plate 36; the axial limiting plate 72 is fixedly installed at the lower end of the guide rod 71 and is arranged in a spaced manner with the top plate 36; the one-way valve plate 73 is arranged between the axial limiting plate 72 and the top plate 36, and is installed on the guide rod 71 and axially slides with the guide rod 71. During the upward compression movement of the plunger 5, the gas pressure in the compression chamber 42 is greater than the external atmospheric pressure, and the gas in the compression chamber 42 pushes the one-way valve plate 73 to slide upward so that the one-way valve plate 73 is attached to the lower end surface of the top plate 36 to close the second inflation port 32; during the downward pulling movement of the plunger 5, the gas pressure in the compression chamber 42 is less than the external atmospheric pressure, and the external gas pushes the one-way valve plate 73 to slide downward to reset, so that the one-way valve plate 73 is arranged in a spaced manner with the lower end surface of the top plate 36, and the second inflation port 32 is opened. The one-way valve plate 73 can be connected to the top plate 36 or the axial limiting plate 72 by an elastic member, which can be a rubber elastic member or a coil spring. The one-way valve plate 73 can be a rigid valve plate or an elastic valve plate. In order to prevent the second inflation port 32 from leaking when the plunger 5 extrudes the compression chamber 42, it is necessary to ensure the flatness of the upper end surface of the rigid valve plate and the lower end surface of the top plate 36 so that the one-way valve plate 73 and the top plate 36 are sealed together, that is, the machining precision of the one-way valve plate 73 and the top plate 36 is required to be high, and the cost is also high. Therefore, the one-way valve plate 73 is preferably an elastic valve plate, and when the plunger 5 extrudes the compression chamber 42, the gas pressure in the compression chamber 42 will cause the elastic valve plate to elastically deform and tightly adhere to the top plate 36, thereby improving the sealing performance of the second inflation port 32. The guide rod 71 and the axial limiting plate 72 can be an integral structure or independent parts. The guide rod 71 can be installed on the top plate 36 by welding, interference pressure connection, or threaded connection, and specifically, the guide rod 71 is threadedly connected to the top plate 36, and the guide rod 71 and the axial limiting plate 72 are an integral structure, which facilitates the assembly, disassembly, and replacement of the one-way valve plate 73.

[0040] The plunger 5 slides up and down in the cylinder cavity of the piston 3 to adjust the volume and air pressure of the compression gas chamber 42, and to provide power for the input, pressurization and output of the gas in the compression gas chamber 42. In order to avoid the plunger 5 moving to the upper limit position and rigidly colliding with the top plate 36 due to the excessive compression movement of the air spring caused by the bad road conditions, preferably, a buffer limiting piece 43 is arranged in the compression gas chamber 42, the buffer limiting piece 43 is located between the plunger 5 and the top plate 36, and the buffer limiting piece 43 is used for limiting the axial position of the plunger 5 in the cylinder cavity of the piston 3, so as to avoid the rigid collision between the plunger body 5 and the inner top wall of the piston 3, and improve the driving comfort of the vehicle. The buffer limiting piece 43 is an elastic piece, which can be an elastic buffer piece made of rubber or a spiral spring. The buffer limiting piece 43 can be installed on the plunger 5 or arranged at the top of the cylinder cavity of the piston 3.

[0041] The plunger 5 can be an integral structure formed integrally or a combined structure assembled by multiple parts; can be a rubber column structure or a combined structure assembled by a skeleton and a rubber ring wrapped outside the skeleton. Preferably, the plunger 5 comprises a plunger body 51, an annular groove coaxial with the plunger body 51 is arranged on the outer side of the plunger body 51, a first sealing ring 52 is arranged in the annular groove, the first sealing ring 52 protrudes from the outer side of the plunger body 51 and is in sealing cooperation with the inner side wall of the piston 3, so as to improve the sealing performance of the compression gas chamber 42. As a further preferred, an annular part integrally formed with the first sealing ring 52 and protruding upward from the upper end surface of the plunger body 51 is arranged on the first sealing ring 52, and the annular part is the buffer limiting piece 43, so as to simplify the structure.

[0042] The plunger 5 can be vertically fixedly connected with the base 1 or hinged with the base 1; the plunger 5 can be directly connected with the base 1 or connected with the base 1 through other connecting pieces. Preferably, a connecting rod 6 is arranged in the main gas chamber 41, the upper end of the connecting rod 6 is hinged with the plunger 5 through a universal ball head, and the lower end of the connecting rod 6 is detachably connected with the base 1. The connecting rod 6 and the base 1 can be deflected at a certain angle relative to the plunger 5 to adapt to the relative deflection of the base 1 and the piston 3 during the extension and contraction movement of the air spring. The outer diameter of the connecting rod 6 should be smaller than the inner diameter of the axial limiting part 34 of the ring plate structure, so as to be connected with the base 1 after passing through the cylinder cavity of the piston 3 from top to bottom.

[0043] The connecting rod 6 and the base 1 can be connected by bolts or pins. Specifically, the base 1 is provided with an axial through limiting stepped hole, and a large hole of the limiting stepped hole is located on a side close to the main gas chamber 41; the lower part of the connecting rod 6 is provided with a shaft ring 61 integrally formed therewith, the upper part of the connecting rod 6 below the shaft ring 61 is provided with a second sealing ring 62, and the connecting rod 6 below the second sealing ring 62 is provided with a threaded section 63; the second sealing ring 62 is in sealing cooperation with the connecting rod 6; the connecting rod 6 penetrates through the limiting stepped hole, the second sealing ring 62 is in sealing cooperation with the hole wall of the large hole of the limiting stepped hole, and the shaft ring 61 is in axial abutment with the top surface of the base 1; the threaded section 63 protrudes downward from the base 1 and is connected with a fastening nut 64, and the upper end surface of the fastening nut 64 is closely attached to the base 1. The outer diameter of the shaft ring 61 is greater than the hole diameter of the large hole 11 of the limiting stepped hole. The shaft ring 61 and the fastening nut 64 cooperate to position and install the connecting rod 6 in the limiting stepped hole of the base 1, and the second sealing ring 62 is used to seal the gap between the limiting stepped hole and the connecting rod 6, so as to ensure the air tightness of the main gas chamber 41.

[0044] During installation, the connecting rod 6 is first connected with the plunger 5, then the connecting rod 6 is inserted into the column cavity from the upper end of the piston 3, the connecting rod 6 penetrates through the column cavity of the piston 3 from top to bottom and drives the plunger 5 to enter the column cavity of the piston 3, the axial limiting part 33 limits the plunger 3 in the column cavity of the piston 3, the lower end of the connecting rod 6 penetrates through the limiting stepped hole of the base 1 to make the shaft ring 61 abut against the upper end surface of the base 1 to axially pre-position the connecting rod 6, make the second sealing ring 62 in sealing cooperation with the connecting rod 6, and position and install the connecting rod 6 on the base 1 through the fastening nut 64. Finally, the sealing top plate 34 is sealingly welded in the column cavity of the piston 3 to seal the compressed gas chamber 42.

[0045] As a further preferred, the base 1 is provided with a downward protruding annular part 11, the annular part 11 and the base 1 form an installation cavity 12 with an opening downward, and the lower end of the threaded section 63 on the connecting rod 6 and the fastening nut 64 are located in the installation cavity 12. The connecting rod 6 and the fastening nut 64 are prevented from interfering with other structures outside the air spring.

[0046] In the utility model, "upper", "lower", "top", "bottom", "inner", "outer" are relative position relations, and cannot be understood as a limitation on specific orientation. The embodiments of the specific embodiments are preferred embodiments of the utility model, and are not limited to the protection scope of the utility model, so that: any equivalent changes made according to the structure, shape, principle of the utility model should be covered in the protection scope of the utility model.

Claims

1. An air spring comprising a base (1), a gas bag (2) and a piston (3), the base (1) sealing a lower port of the gas bag (2), the piston (3) sealing an upper port of the gas bag (2), the base (1), the gas bag (2) and the piston (3) surrounding a closed gas cavity; characterized in that: the piston (3) has a downwardly open cylinder cavity therein, a plunger (5) being arranged in the cylinder cavity and axially slidingly fitted with the inner side wall of the piston (3), the plunger (5) being sealingly fitted with the inner side wall of the piston (3), the lower end of the plunger (5) being connected to the base (1); the plunger (5) separates the gas cavity into a main gas chamber (41) and a compressed gas chamber (42) which are isolated from each other, the compressed gas chamber (42) being located on the upper side of the top surface of the plunger (5); the piston (3) is provided with a first air charging port (31) connected to the main gas chamber (41), a second air charging port (32) connected to the compressed gas chamber (42) and an air outlet (33) connected to the compressed gas chamber (42); the second air charging port (32) is provided with a one-way valve (7) leading to the compressed gas chamber (42). the lower end of the piston (3) is provided with an axial limiting portion (34) protruding inwardly from the inner side wall of the piston (3).

2. The air spring of claim 1, wherein: the axial limiting portion (34) is an annular plate structure integrally formed with the piston (3), the axial limiting portion (34) of the annular plate structure being coaxially arranged with the piston (3); 3. The air spring of claim 2, wherein: the piston (3) comprises a piston cylinder (35) with open ends and a top plate (36) welded to the upper portion of the piston cylinder (35), the top plate (36) sealing the upper port of the piston cylinder (35), the top plate (36) and the inner wall of the piston cylinder (35) surrounding the cylinder cavity of the piston (3); the plunger (5) is detachably connected to the base (1). the inner side wall of the upper portion of the piston cylinder (35) is provided with a limiting step (37), the top plate (36) being located in the piston cylinder (35) and the lower end surface of the top plate (36) being in contact with the top surface of the limiting step (37).

4. The air spring of claim 3, wherein: the second air charging port (32) is arranged on the top plate (36), the second air charging port (32) being covered with filter cotton (38); 5. The air spring of claim 4, wherein: the upper surface of the filter cotton (38) is located below the upper end surface of the piston cylinder (35). a buffer limiting member (43) is arranged in the compressed gas chamber (42), the buffer limiting member (43) being located between the plunger (5) and the top plate (36).

6. The air spring of claim 3, wherein: the one-way valve (7) comprises a guide rod (71), an axial limiting plate (72) and a one-way valve plate (73) arranged in the compressed gas chamber (42).

7. The air spring of claim 3, wherein: ​ The guide rod (71) is parallel to the axis of the plunger (5), the upper end of the guide rod (71) is connected to the top plate (36); the axial limiting plate (72) is fixedly installed at the lower end of the guide rod (71) and is arranged in a spaced manner with the top plate (36); the one-way valve plate (73) is arranged between the axial limiting plate (72) and the top plate (36), and the one-way valve plate (73) is installed on the guide rod (71) and is in axial sliding fit with the guide rod (71).

8. The air spring of claim 6, wherein: The plunger (5) comprises a plunger body (51), an annular groove coaxial with the plunger body (51) is arranged on the outer side of the plunger body (51), a first sealing ring (52) is arranged in the annular groove, and the first sealing ring (52) protrudes from the outer side of the plunger body (51) and is in sealing fit with the inner side wall of the piston (3); An annular part integrally formed with the first sealing ring (52) and protruding upward from the upper end surface of the plunger body (51) is arranged on the first sealing ring (52), and the annular part is the buffer limiting part (43).

9. The air spring of any of claims 1-8, wherein: A connecting rod (6) is arranged in the main gas chamber (41), the upper end of the connecting rod (6) is hingedly connected to the plunger (5) through a universal ball head, and the lower end of the connecting rod (6) is detachably connected to the base (1).

10. The air spring of claim 9, wherein: An axial through limiting stepped hole is arranged on the base (1), and the large hole of the limiting stepped hole is located on the side close to the main gas chamber (41); A shaft ring (61) integrally formed with the connecting rod (6) is arranged on the lower part of the connecting rod (6), a second sealing ring (62) is arranged on the connecting rod (6) below the shaft ring (61), a threaded section (63) is arranged on the connecting rod (6) below the second sealing ring (62); the second sealing ring (62) is in sealing fit with the connecting rod (6); The connecting rod (6) penetrates through the limiting stepped hole, the second sealing ring (62) is in sealing fit with the hole wall of the large hole of the limiting stepped hole, the shaft ring (61) is in axial abutment with the top surface of the base (1); the threaded section (63) protrudes downward from the base (1) and is connected with a fastening nut (64) thereon, and the upper end surface of the fastening nut (64) is closely attached to the base (1).

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