Diaphragm for air spring and air spring

Abstract

The invention provides a diaphragm for an air spring and the air spring. The diaphragm (3) is provided with a pair of ring-shaped bead sections (31, 32). Wherein the tire bead part (31) comprises a tire bead inner surface (31a) facing the inner side in the axial direction, and the tire bead inner surface (31a) is provided with a ventilation path forming part (80). The air passage forming section (80) is configured so as to form an air passage between the bead inner surface (31a) and an imaginary plane (VP) that is orthogonal to the axial direction and is in contact with the bead inner surface (31a), the air passage leading from a region (Ai) that is further inward than the bead inner surface (31a) in the radial direction to a region (Ao) that is further outward than the bead inner surface (31a) in the radial direction.

Description

Technical Field

[0001] The present disclosure relates to a diaphragm for an air spring and an air spring including the diaphragm. Background Art

[0002] Air springs have traditionally been installed in railway vehicles, automobiles, and various industrial machinery. Typically, an air spring has a cylindrical diaphragm inserted between a lower member and an upper member. The diaphragm has a pair of annular bead portions, one of which is attached to the lower member and the other to the upper member. This ensures the diaphragm's airtightness, while its internal space acts as an air chamber and provides elasticity. For example, Patent Documents 1 and 2 describe such air spring structures.

[0003] In the installation of the air spring, the steps are to install the air spring on the installation object such as a railway vehicle (installation process), and then supply air to the diaphragm (air supply process). In the installation process, since the air spring is in a deflated state (leaking state), the upper part, which has dropped due to the weight of the installation object, contacts the lower part (see Figure 4 ). In the air supply process, the diaphragm is expanded by filling with air, and the air spring becomes inflated. Therefore, the upper part rises due to the action of the internal pressure and separates from the lower part (refer to Figure 1 ).

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2023-13426

[0007] Patent Document 2: Japanese Patent Application Laid-Open No. 2019-108919 Summary of the Invention

[0008] [Technical problem to be solved by the invention]

[0009] The inventors of the present invention investigated the installation of air springs and discovered that the presence of the bead portion of the diaphragm could interfere with the transition from the deflated state to the inflated state. More specifically, they discovered that if the bead portion were misaligned due to slight dimensional deviations of the diaphragm, the bead portion would seal the lower and upper parts that were close to each other in the deflated state (see Figure 5 ), which hinders the supply of air to the diaphragm.

[0010] Furthermore, the phenomenon of the bead portion being misaligned and sealing the lower and upper components is not limited to air spring installation. Although the probability of this occurring is low, it can also occur during maintenance work, for example, when air is removed from an inflated air spring, temporarily deflated, and then air is supplied to inflate it again.

[0011] The present disclosure has been made in view of the above-mentioned actual situation, and an object thereof is to provide an air spring diaphragm and an air spring capable of supplying air to the diaphragm even when the bead portion seals between the lower member and the upper member.

[0012] Solutions for solving technical problems

[0013] The diaphragm for an air spring disclosed herein comprises a pair of annular bead portions, at least one of the pair of bead portions includes an inner bead surface facing axially inward, an air path forming portion is provided on the inner bead surface, the air path forming portion is constructed in such a way as to form an air path between an imaginary surface that is orthogonal to the axial direction and in contact with the inner bead surface and the inner bead surface, the air path extending from an area radially inward of the inner bead surface to an area radially outward.

[0014] The air spring of the present disclosure is formed by inserting the above-mentioned air spring diaphragm between a lower member and an upper member. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a longitudinal sectional view showing an air spring according to one embodiment of the present disclosure.

[0016] Figure 2 This is a longitudinal cross-sectional view of the diaphragm for the air spring.

[0017] Figure 3 It is a top view showing the lower panel and the inner surface of the tire bead.

[0018] Figure 4 It is a longitudinal sectional view of the air spring showing a deflated state during the setting process.

[0019] Figure 5 It is a longitudinal sectional view of the air spring showing a deflated state during the setting process.

[0020] Figure 6 It is a side view showing the groove as the air passage forming portion.

[0021] [Description of Reference Numerals]

[0022] 1: Lower component; 2: Upper component; 3: Diaphragm for air spring; 4: Lower panel; 6: Upper panel; 31: Bead portion; 31a: Bead inner surface; 32: Bead portion; 41: Bead seat portion; 41t: Tapered surface; 80: Air passage forming portion; 81: Groove. DETAILED DESCRIPTION

[0023] An embodiment of the present disclosure will be described with reference to the accompanying drawings.

[0024] Figure 1 This is a longitudinal sectional view of the air spring of this embodiment, showing half of the air spring cut along the central axis P (at Figure 4 、 Figure 5 The same is true for Figure 1 As shown, the air spring 10 has a structure in which an air spring diaphragm 3 (hereinafter referred to as "diaphragm 3") is interposed between a lower member 1 and an upper member 2. The lower member 1 is positioned below the upper member 2. The diaphragm 3 includes a pair of annular beads 31 and 32. The beads 31 are attached to the lower member 1, and the beads 32 are attached to the upper member 2, thereby ensuring the airtightness of the diaphragm 3.

[0025] In this embodiment, an example of an air spring for a railway vehicle in which an air spring 10 is mounted on a railway vehicle is shown. The lower part 1 is connected to the upper surface of a trolley 91, which is an installation object on the suspension side. The upper part 2 is connected to the bottom surface of a vehicle body 92, which is an installation object on the target suspension side. The trolley 91 and the vehicle body 92 are schematically shown. The upper panel 6 described later is composed of a component different from the bottom surface of the vehicle body 92, but can also be composed of a part of the bottom surface of the vehicle body 92. In addition, the air spring disclosed in the present invention is not limited to use in railway vehicles, but can also be an air spring for automobiles, various industrial machines, etc.

[0026] Figure 2 This is a longitudinal cross-sectional view of the diaphragm 3. The diaphragm 3 is an annular membrane body having a bead portion 31, a bead portion 32, and a main body portion 33 located between the bead portion 31 and the bead portion 32, and is formed into a cylindrical shape as a whole. The diaphragm 3 is formed of an elastic material such as rubber and has flexibility. Figure 2 , the cross-sectional shape of the diaphragm 3 in the state of being assembled into the air spring 10 is shown, but the cross-sectional shape of the diaphragm 3 before being assembled into the air spring 10 may be different from this.

[0027] Here, the axial direction is the direction along the central axis P, which is equivalent to the height direction of the air spring 10 ( Figure 1 、 Figure 2The side close to the inner space of the diaphragm 3 is the axial inner side, and the side opposite thereto is the axial outer side. Therefore, the axial inner side of the bead portion 31 and the lower part 1 is the upper side, and the axial inner side of the bead portion 32 and the upper part 2 is the lower side. The radial direction is the direction perpendicular to the central axis P, which is equivalent to Figure 1 、 Figure 2 The side closer to the central axis P is the radially inner side, and the side farther from the central axis P is the radially outer side. The circumferential direction is the direction around the central axis P.

[0028] like Figure 2 As shown in the enlarged view, the bead portion 31 includes a bead inner surface 31a facing axially inward, a bead bottom surface 31b facing radially inward, and a bead outer surface 31c facing axially outward. The bead inner surface 31a extends radially outward from the axially inner end of the bead bottom surface 31b, and the bead outer surface 31c extends radially outward from the axially outer end of the bead bottom surface 31b. In the diaphragm 3 assembled into the air spring 10, the bead inner surface 31a faces the internal space of the diaphragm 3, and the bead bottom surface 31b and the bead outer surface 31c are in close contact with the bead seat portion 41 of the lower part 1 (see Figure 1 ).

[0029] A circumferentially extending annular bead core 34 is embedded in each of the pair of bead portions 31 and 32. The bead core 34 is composed, for example, of a bundle of bead wires and has a substantially rectangular cross-section. Furthermore, a reinforcing layer 35 is embedded in the diaphragm 3. The reinforcing layer 35 is folded over and disposed between the bead portions 31 and 32 to sandwich the bead core 34. In this embodiment, the reinforcing layer 35 is formed by stacking multiple (specifically, two) plies of rubber covered reinforcing cords arranged in a specific direction. The reinforcing cords are preferably made of organic fibers such as nylon.

[0030] In this embodiment, the pair of bead portions 31 and 32 have different inner diameters. The inner diameter of the bead portion 31 is smaller than that of the bead portion 32, and the bead inner surface 31a of the bead portion 31, which has a relatively smaller inner diameter, faces the lower surface of the upper panel 6, which will be described later. In this embodiment, a so-called Mann-A-N type diaphragm 3 is used, but this is not limited to this. Therefore, for example, the inner diameter of the bead portion 31 and the inner diameter of the bead portion 32 may be substantially the same, or the inner diameter of the bead portion 31 may be larger than the inner diameter of the bead portion 32.

[0031] like Figure 1As shown, the lower member 1 includes a lower panel 4 formed in a circular plate shape, with a bead portion 31 mounted on the outer periphery of the lower panel 4. A bead seat 41 is provided on the lower member 1, and the bead portion 31 is mounted on the bead seat 41 in a self-sealing manner. The bead portion 31 is pressed downward by the internal pressure of the diaphragm 3, thereby tightly contacting the bead seat 41, thereby sealing the space between the diaphragm 3 and the lower member 1.

[0032] The bead seat portion 41 is formed with a tapered surface 41t that tapers axially inward. The bead bottom surface 31b of the bead portion 31 abuts against the tapered surface 41t from the radially outer side. This structure ensures that even if the inner diameter of the bead portion 31 increases over time, the bead portion 31, pressed downward by the internal pressure, remains in close contact with the bead seat portion 41, ensuring a sufficient engagement pressure and maintaining a suitable seal.

[0033] An elastic mechanism 5, which functions as a stopper, is located on the underside of the lower panel 4. The elastic mechanism 5 comprises a top plate 51, a bottom plate 52, and a laminated rubber body 53 sandwiched between the top and bottom plates 51 and 52. The laminated rubber body 53 comprises an alternating layer of rubber, an elastic body, and steel, a rigid body, forming a cylindrical shape. In this embodiment, the rubber and steel are formed into annular plates parallel to the radial direction, but this is not limiting. For example, a tapered stopper structure may be formed in which the rubber and steel are tapered upwards into a tapered cylindrical shape. The elastic mechanism 5 may also be omitted.

[0034] The lower panel 4 is formed to have a larger diameter than the top panel 51 and is configured to be mounted on the top panel 51 in a manner that covers the top panel 51. A through hole 42 is provided on the lower panel 4, and the through hole 42 is used to install a fixing member 45 that fixes the lower panel 4 to the top panel 51. Figure 3 As shown, through holes 42 are formed at multiple locations (six in this embodiment) in the circumferential direction. The head of the fixing member 45 is received in the through hole 42 to prevent it from protruding upward from the upper surface of the lower panel 4. The fixing member 45 and the fixing member 63 described later are, for example, bolts.

[0035] A sliding sheet 43 is mounted on the upper surface of the lower panel 4. The sliding sheet 43 is formed from a material having excellent sliding properties, such as a fluororesin (e.g., PTFE). The upper surface of the sliding sheet 43 is positioned above the upper surface of the lower panel 4. Therefore, even if the air spring 10 becomes deflated due to air leakage during actual use, the upper member 2, which descends along with the vehicle body 92, will contact the lower member 1 via the sliding sheet 43 and be supported by the elastic mechanism 5. When driving in this state, the sliding sheet 43 reduces the frictional resistance when the lower member 1 and the upper member 2 slide.

[0036] The sliding piece 43 is arranged at a position avoiding the through hole 42. In addition, a space 44 where the sliding piece 43 is not installed is formed at least at one place in the circumferential direction. Figure 3 As shown, the space 44 is open to the center and the periphery of the lower panel 4 when viewed from above. Figure 3 In the example of (A), a rectangular sliding piece 43 is arranged in each space between the through holes 42 adjacent in the circumferential direction. In addition, the shape of the sliding piece 43 is not particularly limited, and for example, a rectangular sliding piece 43 may be used. Figure 3 (B) The sliding piece 43 is an arc shape when viewed from above. Figure 3 In (A), there are six spaces 44 formed. Figure 3 In (B), three spaces 44 are formed.

[0037] like Figure 1 As shown, the upper member 2 includes a disc-shaped upper panel 6 and an annular bead pressing member 7 mounted to the lower side of the outer periphery of the upper panel 6 via a fixing member 63. The bead portion 32 is mounted between the upper panel 6 and the bead pressing member 7. The upper member 2 is provided with a bead seat 61, and the bead portion 32 is fastened to the bead seat 61. The bead portion 32 is pressed upward by the fastening action of the fixing member 63, thereby closely contacting the bead seat 61, thereby sealing the space between the diaphragm 3 and the upper member 2.

[0038] A cylindrical boss portion 21 is fitted into the through hole in the center of the upper panel 6. The boss portion 21 is connected to a compressor (not shown) and functions as an air supply port when supplying air to the diaphragm 3. The upper panel 6 is formed to have a larger diameter than the lower panel 4. The lower surface of the upper panel 6, which faces the upper surface of the lower panel 4, is formed by a sliding plate 62. Therefore, in the deflated state, the lower part 1 and the upper part 2 are in contact via the sliding piece 43 and the sliding plate 62 (see FIG. Figure 4 The sliding plate 62 is formed of a material with excellent sliding properties, such as stainless steel, and bears horizontal displacement with minimal resistance when deflated due to air leakage or the like during actual use. The upper panel 6 is not limited to a structure in which the sliding plate 62 is disposed on the lower surface.

[0039] The installation operation of the air spring 10 includes a setting step of setting the air spring 10 on the railway vehicle as the installation object and an air supply step of supplying air to the diaphragm 3 after the setting step. In the setting step, the diaphragm 3 is not yet filled with air. Figure 4 As shown in FIG. 1 , the air spring 10 is in the deflated state, so the upper part 2 is in contact with the lower part 1. During the air supply process, air flowing in from the boss portion 21 is sent to the diaphragm 3 through the space 44. When the diaphragm 3 is expanded by filling with air, the air spring 10 is in the inflated state. Figure 1As shown, under the action of internal pressure, the upper part 2 rises and separates from the lower part 1.

[0040] During the gas supply process, if Figure 5 If the bead portion 31 shown in the figure is displaced, the inner surface 31a of the bead, which is located axially inward (upper) than the upper surface of the lower panel 4, abuts against the lower surface of the upper panel 6. The bead portion 31 seals the space between the lower part 1 and the upper part 2, which may hinder the supply of air to the diaphragm 3 (in the case of the diaphragm 3). Figure 5 In the embodiment, the upper member 2 is separated from the lower member 1, but the upper member 2 may also abut against the lower member 1. Therefore, in this embodiment, the structure described below is adopted, and air can be supplied to the diaphragm 3 even when the bead portion 31 seals the gap between the lower member 1 and the upper member 2.

[0041] The diaphragm 3 includes a pair of annular bead portions 31 and 32, wherein the bead portion 31 includes a bead inner surface 31a facing the axial inner side (upper side). Figure 2 、 Figure 3 As shown, a vent-path forming portion 80 is provided on the bead inner surface 31a. The vent-path forming portion 80 is configured to form a vent between a virtual plane VP, which is orthogonal to the axial direction and in contact with the bead inner surface 31a, and the bead inner surface 31a. This vent extends from an area Ai radially inward relative to the bead inner surface 31a to an area Ao radially outward relative to the bead inner surface 31a. The virtual plane VP is a plane of the counterpart member (i.e., the lower surface of the upper panel 6) that is assumed to be in contact with the bead inner surface 31a in the deflated state.

[0042] According to this structure, Figure 5 As shown, when the bead portion 31 seals the space between the lower member 1 and the upper member 2, an air passage is formed between the bead inner surface 31a and the lower surface of the upper panel 6. This air passage extends from the radially inner region Ai to the radially outer region Ao, thus functioning as a flow path for conveying air flowing in between the lower member 1 and the upper member 2 (primarily through the void 44) ​​into the inner side of the diaphragm 3. Therefore, even when the bead portion 31 seals the space between the lower member 1 and the upper member 2, air can still be supplied to the diaphragm 3.

[0043] In this embodiment, the bead portion 31 seals the gap between the lower member 1 and the upper member 2 during the installation of the air spring 10. However, this phenomenon of the bead portion 31 sealing the gap between the lower member 1 and the upper member 2 is not limited to the installation of the air spring 10. Although the probability of this occurring is low, it can also occur during maintenance work, for example, when air is removed from an inflated air spring 10, temporarily deflated, and then air is supplied to restore the inflated state. In this case, the diaphragm 3 can also achieve the same effect.

[0044] As described above, the vent-path-forming portion 80 forms a vent path that allows air to flow between the bead inner surface 31a and the upper panel 6 (more specifically, from the radially inner region Ai to the radially outer region Ao) when the tire bead inner surface 31a abuts the lower surface of the upper panel 6 in the deflated state. While it is also conceivable to provide the vent-path-forming portion on the counterpart member (i.e., the upper panel 6) that can abut the tire bead inner surface 31a, in this embodiment, the vent-path-forming portion is not provided on the upper panel 6 to prevent damage to the sliding sheet 43 during horizontal displacement in the deflated state and to increase processing costs. However, this is not limiting; a vent-path-forming portion may also be provided on the lower surface of the upper panel 6 in addition to the bead inner surface 31a.

[0045] In this embodiment, the air passage forming portion 80 is formed by a groove 81 that is recessed toward the axial outside. The groove 81 is provided at least at one location in the circumferential direction. Figure 3 As shown, by providing grooves 81 at multiple locations (two locations in this embodiment) in the circumferential direction, air can be efficiently supplied to the diaphragm 3. The grooves 81 extend parallel to the radial direction, but are not limited to this embodiment as long as they form an air passage from the radially inner region Ai to the radially outer region Ao relative to the bead inner surface 31a. The grooves 81 can be provided, for example, by providing a groove-forming projection in a vulcanization mold for the diaphragm 3 or by groove processing the vulcanized diaphragm 3.

[0046] Figure 6 is a side view of the groove 81 observed along the radial direction, which is equivalent to Figure 2 In this embodiment, there is formed Figure 6 (A) shows a rectangular groove 81. The groove 81 has a width W81 (maximum width) and a depth D81 (maximum depth). The dimensions of the width W81 and the depth D81 are not particularly limited. However, from the perspective of ensuring the groove cross-sectional area in a manner that allows efficient air supply, it is preferred that the width W81 be 1 mm or more. In addition, from the perspective of preventing Figure 5 Considering the angle at which the groove 81 is flattened in the deflated state shown, the width W81 is preferably 5 mm or less.

[0047] From Figure 5 In view of the angle of not deforming the groove 81 in the deflated state shown, the depth D81 is preferably 3 mm or more. In addition, the depth D81 is preferably such that the bottom of the groove 81 does not reach the size of the embedded objects such as the reinforcing layer 35 (see Figure 2 As an example, the groove 81 may have a width W81 of 5 mm and a depth D81 of 3 mm. In this embodiment, the width W81 and the depth D81 are constant along the extending direction of the groove 81. However, at least one of the width W81 and the depth D81 may vary along the extending direction of the groove 81.

[0048] The groove shape is not particularly limited and can be Figure 6 Various shapes are shown in (B) to (G). Figure 6 In the examples (A) to (F), the width W81 is larger than the depth D81. If the depth D81 is appropriately reduced to prevent the reinforcement layer 35 from being exposed, and the width W81 is appropriately increased to ensure the groove cross-sectional area, the groove shape is appropriate. Figure 6 In the example of (G), the depth D81 is greater than the width W81. Figure 5 The aspect of not deforming the groove 81 in the deflated state shown is suitable. The depth D81 and the width W81 may also be the same size as each other.

[0049] The vent-path-forming portion 80 is not limited to the groove 81, as long as it can form the aforementioned vent. For example, it can also be formed by a protrusion protruding axially inward. Examples of such protrusions include radially linear protrusions or circumferentially spaced dot-shaped protrusions. However, if air leakage during actual use causes the air spring 10 to enter a deflated state, causing the lower component 1 and upper component 2 to slide, such protrusions could interfere and affect the sliding motion. Therefore, it is preferable to form the vent-path-forming portion 80 as a groove as in this embodiment.

[0050] As described above, the air spring 10 is provided with a bead seat portion 41. The bead portion 31 including the bead inner surface 31a is assembled to the bead seat portion 41 in a self-sealing manner. The tapered surface 41t is formed on the bead seat portion 41. According to this structure, the bead portion 31 is easily displaced in the axial direction due to slight dimensional deviations such as a small inner diameter of the bead portion 31 or a large outer diameter of the bead seat portion 41. Figure 5 Therefore, as shown in the present embodiment, it is particularly useful to provide the air passage forming portion 80 on the bead inner surface 31a.

[0051] In this embodiment, the bead portion 31 including the bead inner surface 31a provided with the venting passage forming portion 80 is assembled in a self-sealing manner. However, the present invention is not limited to this and a structure assembled in a tightening manner may also be employed. Even in a tightening manner, if the bead portion is slightly loosened and thus shifts in position, the lower member 1 and the upper member 2 may be in a deflated state where the bead portion seals the gap between them.

[0052] In this embodiment, the ventilation path forming portion 80 is provided on the bead portion 31 having the relatively smaller inner diameter of the pair of bead portions 31 and 32, but the present invention is not limited thereto. For example, when the diameters of the bead portions 31 and 32 are the same, it is possible that due to the abutment of one bead portion with the other bead portion due to positional displacement, the lower component 1 and the upper component 2 are in a deflated state where the bead portion seals the air between them. Therefore, the ventilation path forming portion may be provided on the bead inner surface 31a of the bead portion 31 facing the bead portion 32 and / or the bead inner surface of the bead portion 32 facing the bead portion 31.

[0053] Those skilled in the art will appreciate that the above embodiments are specific examples of the following methods.

[0054] [1] The diaphragm for an air spring disclosed in the present invention includes a pair of annular bead portions. At least one of the pair of bead portions includes a bead inner surface facing axially inward. An air path forming portion is provided on the bead inner surface, and the air path forming portion is configured to form an air path between an imaginary surface that is orthogonal to the axial direction and in contact with the bead inner surface and the bead inner surface, and the air path extends from an area radially inward of the bead inner surface to an area radially outward. According to this structure, air can be supplied to the diaphragm even when the bead portion seals the lower component and the upper component during the installation operation of the air spring.

[0055] [2] In the air spring diaphragm of the above-mentioned [1], the air passage forming portion may be formed by a groove recessed toward the axial outer side.

[0056] [3] In the air spring diaphragm of [2] above, the width of the groove may be 1 mm or more.

[0057] [4] In the air spring diaphragm of [2] or [3] above, the depth of the groove may be 3 mm or more.

[0058] [5] In any one of the air spring diaphragms described in [1] to [4] above, the pair of bead portions may have different inner diameters, and the air passage forming portion may be provided in the bead portion having a relatively smaller inner diameter among the pair of bead portions.

[0059] [6] The air spring disclosed herein is formed by inserting any one of the air spring diaphragms described in [1] to [5] between a lower member and an upper member. With this structure, air can be supplied to the diaphragm even when the bead seals the space between the lower member and the upper member during installation of the air spring.

[0060] [7] In the air spring of the above-mentioned [6], a bead seat portion may be provided, and the bead portion including the inner surface of the bead is assembled to the bead seat portion in a self-sealing manner.

[0061] [8] In the air spring of [7] above, a tapered surface that tapers axially inward may be formed on the bead seat portion.

[0062] While embodiments of the air spring diaphragm and air spring disclosed herein have been described with reference to the accompanying drawings, it should be understood that the specific configuration is not limited to these embodiments. The scope of the present invention is defined not only by the description of the above embodiments but also by the claims, and encompasses all modifications within the meaning and scope equivalent to the claims.

[0063] The air spring diaphragm and air spring disclosed herein are not limited to the aforementioned embodiments and are not limited to the aforementioned effects. Various modifications and improvements can be made to the air spring diaphragm and air spring disclosed herein without departing from the scope of the present disclosure. Furthermore, the various structures employed in the aforementioned embodiments can be employed in any combination.

Claims

1. A diaphragm for an air spring, characterized in that: The air spring diaphragm includes a pair of annular bead portions. At least one of the pair of bead portions includes a bead inner surface facing axially inward, An air vent forming portion is provided on the inner surface of the tire bead. The air passage forming portion is configured to form an air passage between an imaginary surface perpendicular to the axial direction and in contact with the bead inner surface and the bead inner surface, the air passage extending from a radially inner region to a radially outer region of the bead inner surface.

2. The air spring diaphragm according to claim 1, wherein: The air passage forming portion is formed by a groove recessed toward the axially outer side.

3. The air spring diaphragm according to claim 2, wherein: The width of the groove is greater than 1 mm.

4. The air spring diaphragm according to claim 2, wherein: The width of the groove is 5 mm or less.

5. The air spring diaphragm according to claim 2, wherein: The depth of the groove is greater than 3 mm.

6. The diaphragm for an air spring according to claim 1, wherein The pair of bead portions have inner diameters different from each other, The air passage forming portion is provided in the bead portion having a relatively smaller inner diameter among the pair of bead portions.

7. An air spring, characterized in that: The air spring is formed by inserting the air spring diaphragm according to any one of claims 1 to 6 between a lower member and an upper member.

8. The air spring according to claim 7, wherein: The air spring is provided with a bead seat portion, and a bead portion including an inner surface of the bead is assembled to the bead seat portion in a self-sealing manner.

9. The air spring according to claim 8, characterized in that The bead seat portion is formed with a tapered surface that tapers toward the axial inner side.

10. The air spring according to claim 8, wherein: The bead seat portion is provided on the lower member.

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