Energy accumulators and their manufacturing methods, as well as vehicles

Abstract

This invention provides an accumulator, a method for manufacturing the same, and a vehicle. The accumulator includes a cylinder, a first end cap and a second end cap respectively sealed and welded to opposite ends of the cylinder in an axial direction, and a metal bellows housed within the cylinder. The end of the metal bellows near the first end cap is sealed and welded to the end face of the first end cap facing the inner cavity of the cylinder. At least one of the cylinder, the first end cap, and the second end cap is made of a predetermined steel material selected from QStE380TM structural steel, QStE420TM structural steel, QStE460TM structural steel, QStE500TM structural steel, and QStE550TM structural steel. The accumulator's shell, at least a portion of which is made of predetermined steel possessing both excellent weldability and good mechanical properties, can mitigate or even avoid quality problems such as poor burst performance, poor welding, and brittle fracture of the shell, thereby improving the reliability of the accumulator.

Description

Technical Field

[0001] This invention relates to the field of energy storage technology, and more particularly to an energy storage device and its manufacturing method, as well as a vehicle. Background Technology

[0002] An accumulator is an energy storage device in a hydraulic or pneumatic system, and its reliability is determined by two key factors: material properties and weld quality.

[0003] Currently, the commonly used materials for manufacturing accumulator housings in the automotive industry include 20# steel, Q345E, 30CrMo, and 35CrMo. While 20# steel and Q345E possess excellent weldability, their low tensile strength and poor burst resistance make them unsuitable for manufacturing accumulator housings operating at high pressures. 30CrMo and 35CrMo have higher tensile strength, making them suitable for high-pressure accumulator housings; however, their high carbon equivalent leads to a greater tendency to harden, resulting in poor weldability and a tendency for leaks at weld seams. Furthermore, 30CrMo and 35CrMo have low elongation, while automotive accumulators typically endure vibration and impact loads, increasing the risk of brittle fracture in accumulator housings made from 30CrMo and 35CrMo. Summary of the Invention

[0004] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, the present invention provides an energy accumulator and a method for manufacturing the same, as well as a vehicle, wherein the energy accumulator can mitigate or even avoid quality problems such as poor burst performance, poor welding, and brittle cracking of the casing, thereby improving the reliability of the energy accumulator.

[0005] To achieve the above objectives, in a first aspect, the present invention provides an accumulator, comprising a cylinder, a first end cap and a second end cap respectively sealed and welded to opposite ends of the cylinder in an axial direction, and a metal bellows disposed within the cylinder, wherein one end of the metal bellows near the first end cap is sealed and welded to the end face of the first end cap facing the inner cavity of the cylinder.

[0006] Wherein, at least one of the cylinder, the first end cover and the second end cover is made of a predetermined steel material, which is selected from one of QStE380TM structural steel, QStE420TM structural steel, QStE460TM structural steel, QStE500TM structural steel and QStE550TM structural steel.

[0007] In one embodiment, the cylinder barrel and the first end cap are vacuum electron beam welded, and / or the cylinder barrel and the second end cap are vacuum electron beam welded, and / or the metal bellows and the first end cap are vacuum electron beam welded.

[0008] In one embodiment, the chemical composition of the preset steel, by weight percentage, includes: C 0.06-0.12%, Si 0.05-0.35%, Mn 0.60-1.50%, P 0.01-0.03%, S 0.01-0.03%, Al 0.01-0.08%, with the balance being Fe and unavoidable impurities.

[0009] In one embodiment, the chemical composition of the preset steel, by weight percentage, includes: C 0.10%, Si 0.12%, Mn 1.44%, P 0.01%, S 0.01%, Al 0.02%, with the balance being Fe and unavoidable impurities.

[0010] In one embodiment, the preset steel is selected from one of QStE380TM structural steel, QStE420TM structural steel, QStE460TM structural steel, QStE500TM structural steel and QStE550TM structural steel, and undergoes a heat treatment process, wherein the heat treatment process is a normalizing process or a tempering process.

[0011] In one embodiment, the heat treatment process adopts a normalizing process, which is: normalizing temperature 810-850℃, holding time 3-12 hours, and air cooling to room temperature after holding.

[0012] Secondly, the present invention provides a method for manufacturing an energy storage device, comprising:

[0013] A cylinder barrel, a first end cap, a second end cap, and a metal bellows are provided. At least one of the cylinder barrel, the first end cap, and the second end cap is made of a predetermined steel material, which is selected from one of QStE380TM structural steel, QStE420TM structural steel, QStE460TM structural steel, QStE500TM structural steel, and QStE550TM structural steel.

[0014] One end of the metal bellows is sealed and welded to the end face of the first end cap facing the inner cavity of the cylinder; one axial end of the cylinder is sealed and welded to the second end cap; and

[0015] The metal bellows is housed inside the cylinder from the other end of the cylinder in the axial direction, and the first end cap is sealed and welded to the other end of the cylinder.

[0016] In one embodiment, the cylinder barrel and the first end cap are vacuum electron beam welded, and / or the cylinder barrel and the second end cap are vacuum electron beam welded, and / or the metal bellows and the first end cap are vacuum electron beam welded.

[0017] In one embodiment, the chemical composition of the preset steel, by weight percentage, includes: C 0.06-0.12%, Si 0.05-0.35%, Mn 0.60-1.50%, P 0.01-0.03%, S 0.01-0.03%, Al 0.01-0.08%, with the balance being Fe and unavoidable impurities.

[0018] In one embodiment, the chemical composition of the preset steel, by weight percentage, includes: C 0.10%, Si 0.12%, Mn 1.44%, P 0.01%, S 0.01%, Al 0.02%, with the balance being Fe and unavoidable impurities.

[0019] In one embodiment, at least one of the cylinder, the first end cap, and the second end cap is made of a predetermined steel material, specifically including:

[0020] First, a prototype of at least one of the cylinder, the first end cap, and the second end cap is prepared using the preset steel, and then the prototype is subjected to a heat treatment process.

[0021] Alternatively, the preset steel can be heat-treated first, and then at least one of the cylinder, the first end cap, and the second end cap can be made using the heat-treated preset steel.

[0022] The heat treatment process employs either normalizing or tempering.

[0023] In one embodiment, the heat treatment process adopts a normalizing process, which is: normalizing temperature 810-850℃, holding time 3-12 hours, and air cooling to room temperature after holding.

[0024] Thirdly, the present invention provides a vehicle including an energy storage device as described in any of the above embodiments.

[0025] Compared with the prior art, the present invention has the following advantages: In the accumulator provided by the present invention, at least part of its shell is made of a pre-selected steel with both excellent welding performance and good mechanical properties, thereby reducing or even avoiding quality problems such as poor burst performance, poor welding and brittle cracking of the shell, and meeting the reliability requirements of the accumulator.

[0026] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0028] Figure 1 This is a cross-sectional structural diagram of the energy storage device provided in an embodiment of the present invention.

[0029] Figure 2 This is a flowchart of the method for manufacturing an energy storage device provided in an embodiment of the present invention.

[0030] Explanation of key figure labels:

[0031] 1-Cylinder; 2-First end cover; 3-Second end cover; 4-Metal bellows; 5-Buffer; 6-Snap ring; 7-Sealing ring; 8-Sealing cover; 9-Guide; 10-Air seal cover; 21-Air port; 22-Air chamber; 31-Oil port; 32-Oil chamber.

[0032] The following detailed description, in conjunction with the accompanying drawings, further illustrates the present invention. Detailed Implementation

[0033] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0034] Please see Figure 1 The present invention provides an energy accumulator, which includes a cylinder 1, a first end cap 2 and a second end cap 3 respectively sealed and welded to opposite ends of the cylinder 1 in the axial direction, and a metal bellows 4 housed in the cylinder 1.

[0035] Specifically, such as Figure 1As shown, in an embodiment of the present invention, the first end cap 2 has a gas port 21 communicating with the inner cavity of the cylinder 1, and the second end cap 3 has an oil port 31 communicating with the inner cavity of the cylinder 1; the metal bellows 4 is telescopically disposed inside the cylinder 1, and its end near the first end cap 2 is sealed and welded to the end face of the first end cap 2 facing the inner cavity of the cylinder 1. The end of the metal bellows 4 adjacent to the gas port 21 defines a gas cavity 22 communicating with the gas port 21 between itself and the first end cap 2, and the end of the metal bellows 4 adjacent to the oil port 31 defines an oil cavity 32 communicating with the oil port 31 between itself and the cylinder 1 and the second end cap 3. The gas port 21 is used to introduce gas into the gas cavity 22, and the oil port 31 is used to introduce oil into the oil cavity 32. It is easy to understand that when the pressure in the oil chamber 32 is greater than the pressure in the gas chamber 22, the metal bellows 4 is compressed; and when the pressure in the gas chamber 22 is greater than the pressure in the oil chamber 32, the metal bellows 4 is stretched. The metal bellows 4 can be any existing type of metal bellows, and the working principle of the accumulator is the same as that of existing metal bellows accumulators, which will not be elaborated further.

[0036] It is important to note that, in the embodiments of the present invention, at least one of the cylinder 1, the first end cap 2, and the second end cap 3 is made of a predetermined steel material. This predetermined steel material is selected from one of the following: QStE380TM structural steel, QStE420TM structural steel, QStE460TM structural steel, QStE500TM structural steel, and QStE550TM structural steel, which have low carbon equivalent and good tensile strength and elongation. That is to say, in the accumulator provided by the present invention, at least a portion of its shell is made of the predetermined steel material, which possesses both excellent weldability and good mechanical properties. This reduces or even avoids quality problems such as poor burst performance, poor welding, and brittle cracking of the shell, thereby improving the reliability of the accumulator.

[0037] Preferably, in one embodiment of the present invention, the cylinder 1, the first end cap 2, and the second end cap 3 are all made of the preset steel, so that the material of the entire shell of the accumulator has both excellent welding performance and good mechanical properties, which helps the accumulator avoid quality problems such as poor burst performance, poor welding and brittle cracking of the shell, and meets the reliability requirements of the accumulator.

[0038] Optionally, in embodiments of the present invention, the sealing welds between the cylinder 1 and the first end cover 2, between the cylinder 1 and the second end cover 3, and between the metal bellows 4 and the first end cover 2 can all be achieved using vacuum electron beam welding, plasma welding, or laser welding. Specifically, in one embodiment of the present invention, vacuum electron beam welding is preferably used to achieve sealing welds between the cylinder 1 and the first end cover 2, between the cylinder 1 and the second end cover 3, and between the metal bellows 4 and the first end cover 2. Using the same welding technology between all components helps improve the performance consistency and sealing consistency of the various welds in the accumulator, and the weld quality is excellent, which helps improve the burst performance of the accumulator and extend its service life.

[0039] Alternatively, in embodiments of the present invention, the chemical composition of the preset steel, by weight percentage, includes: C 0.06-0.12%, Si 0.05-0.35%, Mn 0.60-1.50%, P 0.01-0.03%, S 0.01-0.03%, Al 0.01-0.08%, with the balance being Fe and unavoidable impurities. By limiting the chemical composition of the preset steel within a reasonable range, it can be ensured that the preset steel has good material properties.

[0040] Preferably, in one embodiment of the present invention, the chemical composition of the preset steel, by weight percentage, may specifically include: C 0.10%, Si 0.12%, Mn 1.44%, P 0.01%, S 0.01%, Al 0.02%, with the balance being Fe and unavoidable impurities.

[0041] Furthermore, in some embodiments of the present invention, the preset steel is selected from one of the aforementioned structural steels and undergoes a heat treatment process, wherein the heat treatment process employs normalizing or tempering. By performing normalizing or tempering on any of the aforementioned structural steels, the grain size of the steel can be further refined, the mechanical properties of the material can be improved, and the yield strength, tensile strength, and elongation of the preset steel obtained after heat treatment are significantly increased.

[0042] Specifically, in one embodiment of the present invention, the heat treatment process preferably employs a normalizing process. The normalizing process is as follows: under the conditions of a furnace temperature of 660-700℃ and a heating rate of 100-300℃ / h, the furnace temperature is raised to a normalizing temperature of 810-850℃, held for 3-12 hours, and then air-cooled to room temperature. The normalizing temperature is preferably 820-840℃, and more preferably 830℃.

[0043] Of course, in other embodiments of the present invention, the heat treatment process can also be carried out by tempering under medium and low temperature conditions for heat treatment of any of the aforementioned structural steels, which will not be elaborated further.

[0044] Please refer to it again. Figure 1 In an embodiment of the present invention, similar to the structure of an existing metal bellows accumulator, the accumulator also includes components such as a buffer 5, a retaining ring 6, a sealing ring 7, a sealing cover 8, a guide 9, and a sealing cover 10.

[0045] Specifically, such as Figure 1 As shown, after the cylinder 1 and the second end cover 3 are sealed and welded together, the retaining ring 6 is sealed and welded to the inner side of the second end cover 3, and has a through hole connecting the oil port 31 and the inner cavity of the cylinder 1. The buffer 5 is disposed between the second end cover 3 and the retaining ring 6, and at least partially protrudes from the surface of the second end cover 3 and the retaining ring 6 near the metal bellows 4. The sealing ring 7 is fitted into the sealing groove of the second end cover 3. The sealing cap 8 is disposed at the end of the metal bellows 4 near the second end cover 3, and is sealed and welded to the metal bellows 4. The sealing cap 8 is used to separate the air chamber 22 and the oil chamber 32. When the metal bellows 4 is stretched, the buffer 5 can buffer the collision between the sealing cap 8 and the second end cover 3 and the retaining ring 6, thereby preventing abnormal noise from occurring when the accumulator is working. The guide member 9 is disposed between the end of the metal bellows 4 near the second end cap 3 and the sealing cap 8 to ensure that the metal bellows 4 is not worn during compression and stretching. Generally, there is a gap between the outer circumferential surface of the metal bellows 4 and the inner wall of the cylinder 1. In order to ensure that the metal bellows 4 does not swing during compression and stretching, the guide member 9 can be sleeved on the sealing cap 8, and the guide member 9 is in contact with the inner wall of the cylinder 1, thereby preventing the metal bellows 4 from swinging during compression and stretching. The air sealing cap 10 is used to seal the air port 21 after the air is filled into the air chamber 22 through the air port 21, and to seal and weld it to the first end cap 2. In the embodiments of the present invention, any of the components of the buffer member 5, the retaining ring 6, the sealing ring 7, the sealing cap 8, the guide member 9, and the air sealing cap 10 can be existing corresponding components, which will not be described in detail.

[0046] The performance of the energy accumulator provided in one embodiment of the present invention will be compared with that of a conventional bellows energy accumulator in conjunction with Table 1 below. In the accumulator provided in this embodiment of the invention, the cylinder 1, the first end cover 2, and the second end cover 3 are all made of QStE420TM structural steel. The QStE420TM structural steel specifically comprises the following chemical composition by weight percentage: C 0.10%, Si 0.12%, Mn 1.44%, P 0.01%, S 0.01%, Al 0.02%, with the balance being Fe and unavoidable impurities. Furthermore, the cylinder 1, the first end cover 2, and the second end cover 3 are all heat-treated at a normalizing temperature of 830℃, and then welded together using vacuum electron beam welding. In a comparative example, the accumulator's cylinder, first end cover, and second end cover are all made of 35CrMo steel. The 35CrMo steel specifically comprises the following chemical composition by weight percentage: C 0.35%, Si 0.23%, Mn 0.62%, P 0.02%, S 0.01%, Cr 0.93%, Mo 0.18%, Ni 0.10%, with the balance being Fe and unavoidable impurities, and the cylinder, first end cap and second end cap of the accumulator in the comparative example are plasma welded together.

[0047] Table 1

[0048]

[0049]

[0050] As can be seen from the data in Table 1 above, the accumulator provided in this embodiment of the invention uses QStE420TM structural steel and undergoes normalizing treatment at 830℃. The elongation of the material is 27%, which is significantly higher than the elongation of the 35CrMo material used in the comparative example. Furthermore, the tensile strength of the accumulator provided in this embodiment of the invention is higher than 520MPa, and after adjusting the wall thickness, its burst pressure meets the reliability requirements (≥80MPa). Moreover, in the accumulator provided in this embodiment of the invention, the cylinder 1 and end caps (i.e., the first end cap 2 and the second end cap 3) are connected by vacuum electron beam welding, which increases the durability of the accumulator from 100,000 cycles in the comparative example to 1.77 million cycles. The durability is significantly improved, far exceeding the durability standard for accumulators (≥1.3 million cycles). Furthermore, tests show that the failure locations of the accumulator provided in this embodiment of the invention all occur in the middle of the cylinder, and the failure mode is plastic deformation cracking. No oil leakage occurred in the weld, and the shell of the accumulator did not exhibit brittle fracture.

[0051] It should be noted that the above test results are the average values ​​of multiple tests conducted on the energy storage devices provided in the embodiments of the present invention and the energy storage devices in the comparative examples.

[0052] In summary, the accumulator provided in this embodiment of the invention uses a pre-selected steel material with both excellent weldability and good mechanical properties for its shell. After normalizing, it is welded using vacuum electron beam welding, which greatly improves the performance of the shell material. This allows the accumulator to avoid quality problems such as poor burst performance, poor welding, and brittle cracking of the shell, thus meeting the reliability requirements of the accumulator.

[0053] Please see Figure 2 and combined Figure 1 The present invention also provides a method for manufacturing an energy storage device, the method comprising the following steps.

[0054] Step S1 involves providing a cylinder barrel 1, a first end cap 2, a second end cap 3, and a metal bellows 4. At least one of the cylinder barrel 1, the first end cap 2, and the second end cap 3 is made of a predetermined steel material, selected from QStE380TM structural steel, QStE420TM structural steel, QStE460TM structural steel, QStE500TM structural steel, and QStE550TM structural steel. The metal bellows 4 can be any existing metal bellows, and there is no limitation on its use.

[0055] Step S2: One end of the metal bellows 4 is sealed and welded to the end face of the first end cover 2 facing the inner cavity of the cylinder 1, and one axial end of the cylinder 1 is sealed and welded to the second end cover 3.

[0056] Step S3: The metal bellows 4 is housed inside the cylinder 1 from the other end of the cylinder 1 in the axial direction, and the first end cap 2 is sealed and welded to the other end of the cylinder 1.

[0057] In the accumulator manufactured using the manufacturing method provided in the embodiments of the present invention, at least part of its shell is made of the preset steel with both excellent welding performance and good mechanical properties, thereby reducing or even avoiding quality problems such as poor burst performance, poor welding and brittle cracking of the shell, and improving the reliability of the accumulator.

[0058] Preferably, in one embodiment of the present invention, the cylinder 1, the first end cap 2, and the second end cap 3 are all made of the preset steel, so that the material of the entire shell of the accumulator has both excellent welding performance and good mechanical properties, which helps the accumulator avoid quality problems such as poor burst performance, poor welding and brittle cracking of the shell, and meets the reliability requirements of the accumulator.

[0059] Optionally, in embodiments of the present invention, the sealing welds between the cylinder 1 and the first end cover 2, between the cylinder 1 and the second end cover 3, and between the metal bellows 4 and the first end cover 2 can all be achieved using vacuum electron beam welding, plasma welding, or laser welding. Specifically, in one embodiment of the present invention, vacuum electron beam welding is preferably used to achieve sealing welds between the cylinder 1 and the first end cover 2, between the cylinder 1 and the second end cover 3, and between the metal bellows 4 and the first end cover 2. Using the same welding technology between all components helps improve the performance consistency and sealing consistency of the various welds in the accumulator, and the weld quality is excellent, which helps improve the burst performance of the accumulator and extend its service life.

[0060] Alternatively, in embodiments of the present invention, the chemical composition of the preset steel, by weight percentage, includes: C 0.06-0.12%, Si 0.05-0.35%, Mn 0.60-1.50%, P 0.01-0.03%, S 0.01-0.03%, Al 0.01-0.08%, with the balance being Fe and unavoidable impurities. By limiting the chemical composition of the preset steel within a reasonable range, it can be ensured that the preset steel has good material properties.

[0061] Preferably, in one embodiment of the present invention, the chemical composition of the preset steel, by weight percentage, may specifically include: C 0.10%, Si 0.12%, Mn 1.44%, P 0.01%, S 0.01%, Al 0.02%, with the balance being Fe and unavoidable impurities.

[0062] In one possible implementation, at least one of the cylinder 1, the first end cap 2, and the second end cap 3 in step S1 is made of a predetermined steel material. Specifically, it may include: firstly, using the predetermined steel material, a prototype of at least one of the cylinder 1, the first end cap 2, and the second end cap 3 is prepared, and then the prototype is subjected to a heat treatment process.

[0063] In another possible implementation, at least one of the cylinder 1, the first end cap 2, and the second end cap 3 in step S1 is made of a predetermined steel material. Specifically, it may include: first performing a heat treatment process on the predetermined steel material, and then using the heat-treated predetermined steel material to prepare at least one of the cylinder 1, the first end cap 2, and the second end cap 3.

[0064] In the above embodiments, the heat treatment process employs either normalizing or tempering. It is understood that, in the embodiments of the present invention, after heat treatment of any of the aforementioned structural steels through normalizing or tempering, the grain size of the steel can be further refined, the mechanical properties of the material can be improved, and the yield strength, tensile strength, and elongation of the pre-designed steel obtained after heat treatment are significantly increased.

[0065] Specifically, in one embodiment of the present invention, the heat treatment process preferably employs a normalizing process. The normalizing process is as follows: under the conditions of a furnace temperature of 660-700℃ and a heating rate of 100-300℃ / h, the furnace temperature is raised to a normalizing temperature of 810-850℃, held for 3-12 hours, and then air-cooled to room temperature. The normalizing temperature is preferably 820-840℃, and more preferably 830℃.

[0066] Of course, in other embodiments of the present invention, the heat treatment process can also be carried out by tempering under medium and low temperature conditions for heat treatment of any of the aforementioned structural steels, which will not be elaborated further.

[0067] Please refer to it again. Figure 1 In the embodiments of the present invention, similar to the structure of existing metal bellows accumulators, the accumulator also includes components such as buffer 5, retaining ring 6, sealing ring 7, sealing cover 8, guide 9, and sealing cover 10. The structure and function of any of the buffer 5, retaining ring 6, sealing ring 7, sealing cover 8, guide 9, and sealing cover 10 are similar to the structure and function of the corresponding existing components, and will not be described in detail.

[0068] It should be noted that the energy storage device manufactured using the manufacturing method provided in the embodiments of the present invention may include all the structures and features of the energy storage device provided in the foregoing embodiments. For more detailed information, please refer to the foregoing descriptions, which will not be repeated here.

[0069] Furthermore, embodiments of the present invention also provide a vehicle that includes the energy storage device described in any of the above embodiments, and therefore possesses at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated further. The vehicle can be any type of vehicle including an energy storage device, such as a fuel-powered vehicle or a hybrid vehicle, and is not limited thereto.

[0070] In the description of this invention, the terms "embodiment," "specific embodiment," "example," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0071] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. An energy storage device, characterized in that, The device includes a cylinder, a first end cap and a second end cap that are respectively sealed and welded to opposite ends of the cylinder in the axial direction, and a metal bellows housed inside the cylinder, wherein one end of the metal bellows near the first end cap is sealed and welded to the end face of the first end cap facing the inner cavity of the cylinder. The cylinder, the first end cover, and the second end cover are all made of pre-selected steel and heat-treated. The pre-selected steel is selected from one of QStE380TM structural steel, QStE420TM structural steel, QStE460TM structural steel, QStE500TM structural steel, and QStE550TM structural steel. The chemical composition of the pre-designed steel, by weight percentage, includes: C 0.06-0.12%, Si 0.05-0.35%, Mn 0.60-1.50%, P 0.01-0.03%, S 0.01-0.03%, Al 0.01-0.08%, with the balance being Fe and unavoidable impurities; The cylinder barrel and the first end cap are welded by vacuum electron beam welding, the cylinder barrel and the second end cap are welded by vacuum electron beam welding, and the metal bellows and the first end cap are welded by vacuum electron beam welding; the heat treatment process is a normalizing process, which is as follows: normalizing temperature 810-850℃, holding time 3-12 hours, and air cooling to room temperature after holding. The accumulator also includes a buffer, a retaining ring, a sealing cap, and a guide; the retaining ring is sealed and welded to the inner side of the second end cap; the buffer is disposed between the second end cap and the retaining ring, and at least partially protrudes from the surface of the second end cap and the retaining ring near the metal bellows; the sealing cap is disposed at one end of the metal bellows near the second end cap; the guide is sleeved on the sealing cap, and the guide is in contact with the inner wall of the cylinder.

2. The energy storage device as described in claim 1, characterized in that, The chemical composition of the pre-designed steel, by weight percentage, includes: C 0.10%, Si 0.12%, Mn 1.44%, P 0.01%, S 0.01%, Al 0.02%, with the balance being Fe and unavoidable impurities.

3. A method for manufacturing an energy storage device, used to manufacture the energy storage device as described in claim 1, characterized in that, include: The system provides a cylinder barrel, a first end cap, a second end cap, and a metal bellows. The cylinder barrel, first end cap, and second end cap are all made of a pre-selected steel material and subjected to a heat treatment process. The pre-selected steel material is selected from one of QStE380TM structural steel, QStE420TM structural steel, QStE460TM structural steel, QStE500TM structural steel, and QStE550TM structural steel. The chemical composition of the pre-selected steel material, by weight percentage, includes: C 0.06-0.12%, Si 0.05-0.35%, Mn 0.60-1.50%, P 0.01-0.03%, S 0.01-0.03%, Al 0.01-0.08%, with the balance being Fe and unavoidable impurities. The heat treatment process employs a normalizing process, wherein the normalizing temperature is 810-850℃, the holding time is 3-12 hours, and after holding, the material is air-cooled to room temperature. One end of the metal bellows is sealed to the end face of the first end cap facing the inner cavity of the cylinder using vacuum electron beam welding; one axial end of the cylinder is sealed to the second end cap using vacuum electron beam welding; and The metal bellows is housed inside the cylinder from the other end of the cylinder in the axial direction, and the first end cap is sealed to the other end of the cylinder by vacuum electron beam welding.

4. The method for manufacturing an energy storage device as described in claim 3, characterized in that, The chemical composition of the pre-designed steel, by weight percentage, includes: C 0.10%, Si 0.12%, Mn 1.44%, P 0.01%, S 0.01%, Al 0.02%, with the balance being Fe and unavoidable impurities.

5. The method for manufacturing an energy storage device as described in claim 3 or 4, characterized in that, The cylinder, the first end cap, and the second end cap are all made of pre-selected steel and have undergone heat treatment. Specifically, they include: First, the cylinder barrel, the first end cap, and the second end cap are prepared using the preset steel, and then the prototype is subjected to a heat treatment process. Alternatively, the preset steel can be heat-treated first, and then the cylinder, the first end cap, and the second end cap can be made from the heat-treated preset steel.

6. A vehicle, characterized in that, Includes the energy storage device as described in claim 1 or 2.

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