Thermostatic expansion valve

Abstract

The application discloses a thermal expansion valve, comprising a sealing structure, the sealing structure comprising a gas tank cover and a sealing body, the gas tank cover being provided with a filling hole, the filling hole comprising a first hole section and a second hole section, at least the first hole section forming an opening with a larger hole diameter on the outer end surface of the gas tank cover than the second hole section forming an opening with a smaller hole diameter on the inner end surface of the gas tank cover, compared with a straight hole, the sealing body is embedded in the gas tank cover more, and the sealing effect is better; the support part is arranged separately from the welding part, the support part supports the sealing body, prevents the sealing body from excessively sinking into the filling hole when the welding part is pressed, and improves the sealing reliability of the welding structure; the first hole section has a larger hole diameter, compared with a straight hole structure in the related art, the gas tank cover in the technical solution removes more materials, the weight of the gas tank cover can be appropriately reduced, and the cost is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fluid regulation, in particular to a thermal expansion valve. BACKGROUND

[0002] In the thermal expansion valve product, the gas tank head needs to be sealed after being filled, such as the thermal expansion valve disclosed in the patent with the name of a directly sealed diaphragm for expansion valve (publication number: CN2572167), wherein a round hole is arranged on the center line position of the upper cover, and a sealing steel ball or a sealing pin is arranged in the middle of the round hole; the sealing steel ball or the sealing pin is welded with the round hole on the upper cover, but this scheme has problems: the stability of the steel ball on the straight hole of the gas tank cover is poor, and under the action of force and heat during welding, the steel ball tends to slide to the inside of the gas tank head cavity along the hole; if the size of the selected steel ball is too small, the steel ball may be extruded and melted into the hole of the gas tank cover during welding; if the size of the selected steel ball is too large, the area of the contact between the bottom of the steel ball and the hole increases, the welding difficulty increases, the welding effect is not good, and the sealing performance is not guaranteed. SUMMARY

[0003] The present application provides a thermal expansion valve to solve the above technical problems.

[0004] One embodiment of the present application provides a thermal expansion valve, comprising a gas tank head, the gas tank head comprising a sealing structure, the sealing structure comprising a gas tank cover and a sealing body, the gas tank cover being provided with a filling hole, the filling hole comprising a first hole section and a second hole section, the first hole section and the second hole section being arranged in communication, the first hole section being arranged closer to the outer end of the gas tank cover than the second hole section, the aperture of the opening formed by the first hole section on the outer end surface of the gas tank cover being larger than the aperture of the opening formed by the second hole section on the inner end surface of the gas tank cover, a part of the sealing body being embedded in the first hole section, and the sealing body embedded in the first hole section having a part located in the second hole section, the gas tank cover comprising a first side wall and a second side wall, the first side wall forming the first hole section, the second side wall forming the second hole section, the first side wall comprising a support portion, the gas tank cover comprising a welding portion, the sealing body being supported on the support portion and forming a welding seam with the welding portion.

[0005] The heat expansion valve comprises a sealing structure, the sealing structure comprises a gas tank cover and a sealing body, the gas tank cover is provided with a charging hole, the charging hole comprises a first hole section and a second hole section, at least the first hole section has a larger hole diameter of an opening formed at an outer end surface of the gas tank cover than a hole diameter of an opening formed at an inner end surface of the gas tank cover, compared with a straight hole, the sealing body is embedded in the gas tank cover more, and the sealing effect is better; the support part and the welding part are arranged separately, the support part of the first side wall supports the sealing body, prevents the sealing body from excessively sinking into the charging hole when the welding part is pressed, and improves the sealing reliability of the welding structure; the first hole section has a larger hole diameter, compared with a straight hole structure in the related art, the gas tank cover in the technical solution removes more materials, and the weight of the gas tank cover can be appropriately reduced, and the cost is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0006] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the specific embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0007] Figure 1 is a sectional structure schematic view of a heat expansion valve of an embodiment of the present application;

[0008] Figure 2 is a structure schematic view of a sealing body in Figure 1

[0009] Figure 3 is a three-dimensional structure schematic view of an embodiment of a gas tank cover;

[0010] Figure 4 is a sectional structure schematic view of a gas tank cover in Figure 3

[0011] Figure 5 is a structure schematic view of a sealing structure of the first embodiment of the present application;

[0012] Figure 6 is a structure schematic view of a sealing structure of the second embodiment of the present application;

[0013] Figure 7 is a structure schematic view of a sealing structure of the third embodiment of the present application;

[0014] Figure 8 is a structure schematic view of a sealing structure of the fourth embodiment of the present application. DETAILED DESCRIPTION

[0015] ​​The technical solutions of the present application will be described clearly and completely below in conjunction with the drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0016] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0017] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0018] As shown in Figures 1 to 8 The present application provides a thermal expansion valve 100, which includes a gas tank head 3, the gas tank head 3 includes a sealing structure 10 and a gas tank 40, the sealing structure 10 includes a gas tank cover 1 and a sealing body 2, in the present embodiment, the sealing body 2 is spherical, as shown in Figure 1The sealing body 2 can be other shapes, such as a semi-spherical shape, that is, the lower half is spherical, and the upper half can be flat or other shapes. The gas tank cover 1 includes a filling hole 30 for filling the gas tank 40 of the thermal expansion valve with a temperature-sensitive medium, the filling hole 30 includes a first hole section 12 and a second hole section 11, the second hole section 11 is adjacent to the inner end face of the gas tank cover 1, the first hole section 12 is adjacent to the outer end face of the gas tank cover 1, the first hole section 12 has a larger hole diameter than the second hole section 11 at the opening of the outer end face of the gas tank cover 1; wherein a part of the sealing body 2 is embedded in the first hole section 12, and the part of the sealing body embedded in the first hole section 12 is located in the second hole section 11, the gas tank cover 1 includes a first side wall 101 and a second side wall 102, the first side wall 101 forms the first hole section 12, and the second side wall 102 forms the second hole section 11, the first side wall 101 includes a support portion 120, the gas tank cover 1 includes a welding portion 130, the sealing body 2 is supported on the support portion 120 and forms a weld with the welding portion 130, the sealing body 2 is welded to the support portion 120 and forms a seal with the welding portion 130, achieving the sealing of the sealing body 2 and the gas tank cover 1 at the filling hole 30.

[0019] The filling hole 30 of the thermal expansion valve 100 described above includes two sections, that is, the first hole section 12 and the second hole section 11, at least the first hole section 12 has a larger hole diameter than the second hole section 11 at the opening of the outer end face of the gas tank cover 1, a part of the sealing body 2 is embedded in the first hole section 12, compared to a straight hole, the part of the sealing body 2 embedded in the gas tank cover 1 is larger, and the sealing effect is better; and the support portion 120 and the welding portion 130 are separately provided, the support portion 120 supports the sealing body 2, preventing the sealing body 2 from being excessively sunk into the gas tank 40 when the welding is under pressure, and improving the sealing reliability of the welding structure; at the same time, the support portion can also limit the sealing body 2 during welding, reducing the movement of the sealing body 2 during welding. The first hole section 12 has a larger hole diameter, and more material is removed, which can appropriately reduce the weight of the gas tank cover 1 and reduce costs.

[0020] Based on the above scheme, the welding method of the sealing body 2 and the gas tank cover 1 can be resistance welding, the sealing body 2 and the gas tank cover 1 are both conductive materials, the sealing body 2 can be a steel ball, and the filling hole 30 can have an outer large and inner small structure. When the sealing body 2 is embedded in the first hole section 12, it first contacts the welding portion 130, at which time the welding portion 130 supports the sealing body 2, the electrode applies pressure to push the steel ball into contact with the welding portion 130 during welding, the welding portion 130 and the contact part of the sealing body 2 soften and melt, the sealing body 2 gradually approaches the support portion 120 for contact, and the welding is completed, and the weld 123 is located between the inner end face and the outer end face of the gas tank cover 1.

[0021] In this application, the support part 120 and the welding part 130 have various forms, and some of them are illustrated below with reference to the accompanying drawings.

[0022] As attached Figure 4 Appendix Figure 5 In one specific embodiment shown, the sealing body 2 is spherical, specifically a steel ball. The first sidewall 101 is arc-shaped, and the support portion 120 is a section of the first sidewall 101. Specifically, the support portion 120 is the upper section of the first sidewall 101, and the support portion 120 is arc-shaped. A portion of the outer surface of the sealing body 2 contacts and adheres to the surface of the support portion 120. Specifically, a portion of the sealing body 2 contacts the arc-shaped surface of the support portion 120. The welding portion 130 is also located on the first sidewall 101. The 120 is located in the lower section of the first sidewall 101 near the second hole section 11. Before welding, the sealing body 2 contacts the welding part 130, that is, it contacts the lower section of the first sidewall 101. After welding, the support part 120 supports the sealing body 2. The weld 123 is formed between the welding part 130 and the sealing body 2. The weld 123 is located inside the support part 120, avoiding direct exposure to the outside, which can slow down the corrosion of the weld 123 by the external environment to a certain extent and extend the service life of the product. In addition, the sidewall of the support part 120 is curved, and the support part 120 is in contact with the lower surface of the sealing body 2, providing support for the sealing body 2. The structure is more uniformly stressed and has higher connection strength.

[0023] The sealing body 2 can be a steel ball. To be suitable for most thermostatic expansion valves, the diameter D of the sealing body 2 is between 3.1 mm and 4.8 mm: 1 / 8 (in) ≤ D ≤ 3 / 16 (in). The wall thickness t of the gas box cover 1 is ≥ 1 mm. The diameter of the second hole section 11 is also limited in related technologies: b: b ≤ (D-1.2) mm. To prevent the sealing body 2 from sinking too much into the filling hole 30, and since the sidewall of the first sidewall 101 is curved, the diameter of the first hole section 12 gradually decreases from the outer end face of the gas box cover 1 to the connection between the first sidewall 101 and the second sidewall 102. The second hole section 11 is a straight hole. Therefore, the maximum diameter of the first hole section 12 is a ≤ D. At the same time, the support part 120 needs to support the sealing body 2. The height d of the upper edge of the weld 123 from the outer end face of the gas box cover 1 is ≥ 0.3 mm. The width c of weld 123 is ≥0.3mm and can be controlled by welding equipment to ensure that the sealing body 2 and the first sidewall 101 have sufficient welding strength.

[0024] As attached Figure 6In another improved embodiment, the sealing body 2 can be spherical, specifically a steel ball, the first side wall 101 is arc-shaped, the support part 120 includes a first support part 121 and a second support part 122, the first support part 121 is a section of the first side wall 101, the second support part 122 is another section of the first side wall 101, a part of the lower sphere of the sealing body 2 is in contact with the first support part 121, another part of the lower sphere of the sealing body 2 is in contact with the second support part 122, the welding part 130 is also located on the first side wall 101, the welding part 130 is located between the first support part 121 and the second support part 122, before welding, the sealing body 2 is in contact with the welding part 130, after welding, the first support part 121 plays a primary supporting role for the sealing body 2, the first support part 121 is adjacent to the upper end surface of the gas tank cover 1, the second support part 122 plays a secondary supporting role for the sealing body 2, the second support part 122 is adjacent to the second side wall 102, the two support parts make the sealing body 2 more stable; the welding part 130 and the sealing body 2 form a weld 123 therebetween, the weld 123 is located between the first support part 121 and the second support part 122, which avoids being directly exposed to the outside, can slow down the corrosion of the external environment on the weld 123 to a certain extent, and prolongs the service life of the product, and meanwhile, the second support part 122 cooperates with the sealing body 2 to isolate the weld 123 from the temperature-sensing medium inside the gas tank, slowing down the corrosion of the temperature-sensing medium on the weld 123.

[0025] Specifically, the side wall of the first support part 121 is arc-shaped, the first support part 121 is in contact with the lower surface of the sealing body 2 at the contact position, and plays a supporting role for the sealing body 2; the structure is relatively uniform in stress, has higher connection strength, plays a primary supporting role for the sealing body 2; the second support part 122 is arc-shaped, the second support part 122 is in contact with the lower surface of the sealing body 2 at the contact position, and plays a supporting role for the sealing body 2; the structure is relatively uniform in stress, has higher connection strength, and plays a secondary supporting role for the sealing body 2.

[0026] The sealing body 2 can be a steel ball, and for most thermal expansion valves, the diameter D of the sealing body 2 is 1 / 8(in)≤D≤3 / 16(in), between 3.1 and 4.8 mm, the wall thickness t of the gas tank cover 1 is ≥1 mm, and the diameter of the second hole section 11 is also limited in the related art, and the diameter b of the second hole section 11 is b≤(D-1.2)mm. In order to avoid the sealing body 2 from being too deeply inserted into the filling hole 30, and the first side wall 101 is arc-shaped, the diameter of the first hole section 12 is gradually reduced, and thus the maximum diameter a of the first hole section 12 is a≤D. The width c of the welding seam 123 is c≥0.3mm, which can be controlled by welding equipment to ensure that the sealing body 2 and the first side wall 101 have sufficient welding strength. At the same time, the first support part 121 needs to play a primary supporting role for the sealing body 2, and the height d of the upper edge of the welding seam 123 from the outer end surface of the gas tank cover 1 is d≥0.3mm, which is better for supporting effect; the second support part 122 plays a secondary supporting role for the sealing body 2, and the height e of the lower edge of the welding seam 123 from the second side wall 102 is selected so that the second support part 122 has a certain strength.

[0027] As shown in another embodiment, Figure 7 The support part 120 includes a first support part 121 adjacent to the outer end surface of the gas tank cover 1, the contact between the sealing body 2 and the first support part 121 is linear contact or circular ring surface contact, the first side wall 101 includes a first step surface 141 between the first support part 121 and the second side wall 102, the first hole section 12 is a straight hole, the welding part 130 includes part of the first step surface 141 and part of the second side wall 102, the sealing body 2 and the welding part 130 form a welding seam 123, an opening of the second hole section 11 is located at the first step surface 141, and the opening diameter of the second hole section 11 at the first step surface 141 is smaller than the opening diameter of the first hole section 12 at the first support part 121; the wall surface of the first side wall 101 includes the first step surface 141 and a vertical surface, the wall surface of the first side wall 101 is in a straight angle step shape, the second hole section 11 is a straight hole, the wall surface of the second side wall 102 is in a cylindrical shape, and the hole diameter of the first hole section 12 between at least the first step surface 141 and the outer end surface of the gas tank cover 1 is greater than the hole diameter of the second hole section 11. The welding part 130 includes part of the first step surface 141 and part of the second side wall 102, the wall surface of the first side wall 101 is in a straight angle step shape, which is equivalent to the welding seam 123 being formed at the straight angle step, which corrects the structure for strength and improves the sealing reliability of the welding structure.

[0028] The sealing body 2 can be a steel ball. To suit most thermostatic expansion valves, the diameter D of the sealing body 2 is between 3.1 mm and 4.8 mm: 1 / 8 (in) ≤ D ≤ 3 / 16 (in). The wall thickness t of the gas box cover 1 is ≥ 1 mm. Related technologies also limit the diameter of the second hole section 11: b ≤ (D-1.2) mm. To prevent the sealing body 2 from sinking too deep into the filling hole, the maximum diameter a of the first hole section 12 is a ≤ D. Simultaneously, the first support 121 needs to support the sealing body 2. The height d of the upper edge of the weld 123 from the outer end face of the gas box cover 1 is ≥ 0.3 mm. The width c of the weld 123 is ≥ 0.3 mm and can be controlled by welding equipment to ensure sufficient welding strength between the sealing body 2 and the first sidewall 101.

[0029] As attached Figure 8 In another improved embodiment shown, the support portion 120 includes a first support portion 121 and a second support portion 122. The first support portion 121 is adjacent to the outer end face of the air box cover 1, and the second support portion 122 is adjacent to the second hole segment 11. The contact between the sealing body 2 and the first support portion 121 and the second support portion 122 is a line contact or an annular surface contact. The first sidewall 101 includes a first stepped surface 141 and a second stepped surface 142. An opening of the second hole segment 11 is located on the second stepped surface 142. The first stepped surface 141 is located between the first support portion 121 and the second stepped surface 142. The first hole segment 12 is a stepped hole. The diameter of the first hole segment 12 at the first support portion 121 is larger than the diameter at the first stepped surface 141. The diameter of the first hole segment 12 at the first stepped surface 141 is larger than the diameter between the first stepped surface 141 and the second stepped surface 142. The second hole segment 11 is located on the second stepped surface 141. The diameter of the sealing body 2 is smaller than the diameter of the first hole section 11 between the first step surface 141 and the second step surface 142. The welding part 130 includes a portion of the first sidewall 101 between the first step surface 141 and the second step surface 142. The sealing body 2 is spherical, the first hole section 12 is a stepped hole, the wall surface of the first sidewall 101 is a right-angled step, the second hole section 11 is a straight hole, and the wall surface of the second sidewall 102 is cylindrical. At least the diameter of the first hole section 12 between the first step surface 141 and the outer end face of the gas box cover 1 is larger than the diameter of the second hole section 11.

[0030] The sealing body 2 is a steel ball, and is suitable for most thermal expansion valves. The diameter D of the sealing body 2 is 1 / 8(in)≤D≤3 / 16(in), between 3.1mm and 4.8mm, the wall thickness t of the gas tank cover 1 is ≥1mm, and the diameter of the second hole section 11 is also limited in the related art, the diameter b of the second hole section 11 is b≤(D-1.2)mm. In order to avoid the sealing body 2 from being too deeply inserted into the filling hole 30, the first hole section 12 is a stepped hole, and the diameter of the first hole section 12 is steppedly reduced, so that the maximum diameter a of the first hole section 12 is a≤D. The width c of the welding seam 123 is c≥0.3mm, which can be controlled by welding equipment to ensure that the sealing body 2 and the gas tank cover 1 have sufficient welding strength. At the same time, the first support part 121 needs to play a primary supporting role for the sealing body 2, and the height d of the upper edge of the welding seam 123 from the outer end surface of the gas tank cover 1 is d≥0.3mm; the second support part 122 plays a secondary supporting role for the sealing body 2, and the height e of the lower edge of the welding seam 123 from the second side wall 102 is selected to make the second support part 102 have a certain strength.

[0031] It is worth noting that the above-mentioned embodiments can be combined with each other, such as in another specific embodiment in which the stepped hole is a three-step structure, the side wall of the upper step is an arc surface, and the lower step is a right-angle step; or the upper step is a right-angle step, and the side wall of the lower step is an arc surface; the advantages of the above-mentioned embodiments are combined, the supporting force for the sealing body is more uniform, and the sealing reliability of the welding structure is improved.

[0032] The above-mentioned embodiments are only preferred embodiments of the present application, and cannot be used to limit the scope of protection of the present application. Any non-essential changes and replacements made by those skilled in the art on the basis of the present application all belong to the scope of protection required by the present application.

Claims

1. A thermal expansion valve comprising a gas chamber head, the gas chamber head comprising a closure structure, the closure structure comprising a gas chamber cover and a closure body, the gas chamber cover being provided with a charging hole, characterized in that, The filling hole comprises a first hole section and a second hole section, the first hole section and the second hole section are in communication, the first hole section is arranged closer to the outer end of the gas tank cover than the second hole section, the aperture of the opening formed by the outer end surface of the gas tank cover is larger than the aperture of the opening formed by the inner end surface of the gas tank cover, a part of the sealing body is embedded in the first hole section, and the part of the sealing body embedded in the first hole section is located in the second hole section, the gas tank cover comprises a first side wall and a second side wall, the first side wall forms the first hole section, and the second side wall forms the second hole section, the first side wall comprises a support part, the gas tank cover comprises a welding part, the sealing body is supported on the support part and forms a welding seam with the welding part, the sealing body is welded with the welding part first, and the sealing body abuts against the support part after the welding part is melted.

2. The thermal expansion valve according to claim 1, characterized in that: The minimum aperture of the first hole section of the filling hole is larger than the aperture of the second hole section, the support part comprises a first support part, the first support part is adjacent to the outer end surface of the gas tank cover, the sealing body abuts against the first support part, and the welding part is located between the outer end surface and the inner end surface of the gas tank cover.

3. The thermal expansion valve according to claim 2, characterized in that: The sealing body is spherical, the first side wall further comprises a first step surface, the first step surface is located between the first support part and the second side wall, the first hole section is a straight hole, the welding part comprises part of the first step surface and part of the second side wall, and an opening of the second hole section is located on the first step surface.

4. The thermal expansion valve according to claim 2, characterized in that: The sealing body is spherical, the support part further comprises a second support part, the second support part is adjacent to the second hole section, the first side wall comprises a first step surface and a second step surface, an opening of the second hole section is located on the second step surface, the first step surface is located between the first support part and the second step surface, the first hole section is a stepped hole, the aperture of the first hole section at the first support part is larger than the aperture at the first step surface, the aperture of the first hole section at the first step surface is larger than the aperture between the first step surface and the second step surface, the aperture of the second hole section at the second step surface is smaller than the aperture between the first step surface and the second step surface, and the welding part comprises the part of the first side wall between the first step surface and the second step surface.

5. The thermal expansion valve according to claim 3, characterized in that: The first hole section is a stepped hole, the wall surface of the first side wall is a right-angle step, the second hole section is a straight hole, the wall surface of the second side wall is a cylinder, and the aperture of the first hole section between at least the first step surface and the outer end surface of the gas tank cover is larger than the aperture of the second hole section.

6. The thermal expansion valve according to claim 4, characterized in that: The first hole section is a stepped hole, the wall surface of the first side wall is a right-angle step, the second hole section is a straight hole, the wall surface of the second side wall is a cylinder, and the aperture of the first hole section between at least the first step surface and the outer end surface of the gas tank cover is larger than the aperture of the second hole section.

7. The thermal expansion valve according to claim 2, wherein The sealing body is spherical, the first supporting part is arc, part of the outer surface of the sealing body is in surface contact and fit with the first supporting part, and the welding part is located at the first side wall.

8. The thermal expansion valve according to claim 7, characterized in that: The supporting part further comprises a second supporting part adjacent to the second hole section, the first supporting part is arc, another part of the outer surface of the sealing body is in surface contact and fit with the second supporting part, and the welding part is located between the first supporting part and the second supporting part.

9. The thermal expansion valve according to claim 7 or 8, characterized in that The caliber of the first hole section gradually decreases from the outer end surface of the gas tank cover to the connection between the first side wall and the second side wall, and the second hole section is a straight hole.

10. The thermal expansion valve according to any one of claims 3 to 8, wherein, a diameter D of the sealing body: 1 / 8 in ≤ D ≤ 3 / 16 in; a maximum diameter a of the first hole section: a ≤ D; a height d of an upper edge of the welding part from the outer end surface of the gas tank cover: d ≥ 0.3 mm; a diameter b of the second hole section: b ≤ (D-1.2) mm; a width c of the welding seam: c ≥ 0.3 mm; a wall thickness t of the gas tank cover: t ≥ 1 mm.

11. The thermal expansion valve according to claim 9, wherein, a diameter D of the sealing body: 1 / 8 in ≤ D ≤ 3 / 16 in; a maximum diameter a of the first hole section: a ≤ D; a height d of an upper edge of the welding part from the outer end surface of the gas tank cover: d ≥ 0.3 mm; a diameter b of the second hole section: b ≤ (D-1.2) mm; a width c of the welding seam: c ≥ 0.3 mm; a wall thickness t of the gas tank cover: t ≥ 1 mm.

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