Weld bolt

Abstract

To allow a weld bolt and a workpiece to be joined easily.SOLUTION: A weld bolt 100 includes a head 110, a shaft part 120 extending from the head 110, and projections 130 protruding from the head 110 and at least partially located around the shaft part 120. An inner surface 132, which is located at one side where the shaft part 120 is located, of the projection 130 and an outer surface 134, which is located at the opposite side of the inner surface 132, of the projection 130 are not symmetrical shapes. The outer surface 134 of the projection 130 is located offset to the one side relative to an outer peripheral surface 116 of the head 110.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a weld bolt. [Background technology]

[0002] In recent years, various weld bolts have been developed. A weld bolt includes a head, a shaft portion extending from the head, and a protrusion protruding from the head and positioned around the shaft portion.

[0003] Patent Document 1 describes an example of a weld bolt. This weld bolt has an annular protrusion surrounding a shaft portion. The cross section of the annular protrusion is triangular.

[0004] An example of a weld bolt is described in Patent Document 2. This weld bolt has three weld projections arranged around the periphery of the shaft portion. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] China Utility Model No. 210686606 [Patent Document 2] JP 2010-223304 A Summary of the Invention [Problem to be solved by the invention]

[0006] In the weld bolt described in Patent Document 1, the cross section of the annular projection has a symmetrical shape. In the weld bolt described in Patent Document 2, the outer surface of the weld projection opposite the shaft is flush with the outer circumferential surface of the head. However, if the cross section of the projection has a symmetrical shape or the outer surface of the projection is flush with the outer circumferential surface of the head, it may be difficult to join the weld bolt and the workpiece to which the weld bolt is welded to each other.

[0007] One object of the present invention is to facilitate joining of a weld bolt and a workpiece to one another. Other objects of the present invention will become apparent from the description of this specification. [Means for solving the problem]

[0008] One aspect of the present invention is as follows. 1. Head and A shaft portion extending from the head portion; a projection extending from the head and positioned at least partially around the shaft; Equipped with one side surface of the protrusion located on one side where the shaft portion is located and another side surface of the protrusion located on the opposite side to the one side surface are asymmetric in shape, A weld bolt, wherein the other side surface of the projection is positioned offset toward the one side with respect to the outer circumferential surface of the head. 2. The weld bolt described in 1., wherein the angle of the one side of the projection relative to the head is less than the angle of the other side of the projection relative to the head. 3. The weld bolt described in 1. or 2., wherein the projection surrounds the shaft portion. Effect of the Invention

[0009] According to the above-described aspect of the present invention, the weld bolt and the workpiece can be easily joined to each other. [Brief description of the drawings]

[0010] [Figure 1] 1 is a perspective view of a portion of a battery pack according to an embodiment; [Diagram 2] FIG. 2 is a cross-sectional view of a weld bolt according to an embodiment. [Diagram 3] FIG. 3 is an enlarged view of a portion of FIG. 2. [Figure 4] FIG. 4 is a cross-sectional view of a weld bolt according to a first modified example. [Diagram 5] FIG. 11 is a cross-sectional view of a weld bolt according to a second modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, embodiments and modifications of the present invention will be described with reference to the drawings. In all the drawings, similar components are given similar reference numerals and descriptions thereof will be omitted as appropriate.

[0012] Fig. 1 is a perspective view of a portion of a battery pack 10 according to an embodiment. Fig. 2 is a cross-sectional view of a weld bolt 100 according to an embodiment. Fig. 3 is an enlarged view of a portion of Fig. 2. Fig. 2 shows a cross section of the approximate center of the weld bolt 100 in a direction perpendicular to a Z direction described below.

[0013] For the purpose of explanation, an arrow marked with "Z" indicating the Z direction is shown in Figures 1 to 3. The Z direction is the direction from one of head 110 and shank 120 (described later) of weld bolt 100 to the other. Hereinafter, as necessary, the side indicated by the arrow indicating the Z direction will be referred to as the +Z side, and the side opposite to the side indicated by the arrow indicating the Z direction will be referred to as the -Z side.

[0014] A battery pack 10 according to an embodiment will be described with reference to FIG.

[0015] The battery pack 10 according to the embodiment includes a battery module (not shown), a module housing 20, and an attachment member 30.

[0016] The battery module has a plurality of battery cells (not shown). The plurality of battery cells are electrically connected in series, in parallel, or in a combination of series and parallel. The module housing 20 houses the battery module. The module housing 20 has an upper case 22. The upper case 22 covers the upper part of the battery module. Both ends of the mounting member 30 in a direction perpendicular to the Z direction are attached to the outer surface of the +Z side of the side wall 22a perpendicular to the Z direction of the upper case 22 by two welding bolts 100 and two nuts 200. The mounting member 30 is, for example, a pressure release valve. As will be described later with reference to FIG. 2 and FIG. 3, each welding bolt 100 has a head 110 and a shaft 120. Each shaft 120 penetrates the side wall 22a and each end of the mounting member 30 in the Z direction with the head 110 disposed on the inner surface of the -Z side of the side wall 22a. Each shaft portion 120 and each nut 200 are fastened to each other with the side wall 22a and each end of the mounting member 30 disposed between the head portion 110 and the nut 200 in the Z direction. However, the method of fastening the module housing 20 and the mounting member 30 to each other is not limited to the method shown in FIG.

[0017] A weld bolt 100 according to an embodiment will be described with reference to FIGS. 2 and 3, and with reference to FIG. 1 as necessary.

[0018] The weld bolt 100 according to the embodiment has a head 110, a shaft 120, and a protrusion 130. The head 110, the shaft 120, and the protrusion 130 are made of carbon steel for machine construction, such as S45C. However, the head 110, the shaft 120, and the protrusion 130 may be made of a conductor different from the materials exemplified here. The head 110, the shaft 120, and the protrusion 130 are integral with one another.

[0019] The head 110 has a generally circular plate shape with a thickness generally parallel to the Z direction. The head 110 has a seating surface 112, a top surface 114, and an outer peripheral surface 116. The seating surface 112 and the top surface 114 are located opposite each other in the Z direction. The seating surface 112 is located on the +Z side of the head 110. The top surface 114 is located on the -Z side of the head 110. The outer peripheral surface 116 is located on the outer periphery around the head 110 in the Z direction.

[0020] The shaft portion 120 has a generally cylindrical shape with a height generally parallel to the Z direction. The shaft portion 120 extends from a generally central portion of the seat surface 112 in a direction perpendicular to the Z direction. The diameter of the shaft portion 120 in a direction perpendicular to the Z direction is smaller than the diameter of the head portion 110 in a direction perpendicular to the Z direction. The height of the shaft portion 120 in the Z direction is greater than the thickness of the head portion 110 in the Z direction.

[0021] The protrusion 130 protrudes from the seat surface 112 and is at least partially located around the shaft portion 120. The height of the protrusion 130 in the Z direction is less than the height of the shaft portion 120 in the Z direction. In the example shown in FIG. 1, the weld bolt 100 and the upper case 22 are joined to each other with the protrusion 130 welded to the inner surface on the -Z side of the side wall 22a. The protrusion 130 is welded by passing a current through the protrusion 130. Thus, in the embodiment, the upper case 22 is a workpiece to which the weld bolt 100 is welded.

[0022] In the embodiment, the protrusion 130 has a substantially annular shape surrounding the shaft portion 120 as viewed from the Z direction. Therefore, as viewed from the Z direction, the protrusion 130 extends continuously around the shaft portion 120 in the Z direction. Therefore, in the embodiment, compared to a case where a plurality of protrusions 130 are arranged at substantially equal or non-equal intervals around the shaft portion 120 in the Z direction as viewed from the Z direction, the welding length of the protrusion 130 can be secured long around the shaft portion 120 in the Z direction, and the welding strength of the protrusion 130 to the inner surface on the -Z side of the side wall 22a can be improved. Furthermore, in the embodiment, compared to a case where a plurality of protrusions 130 are arranged at substantially equal or non-equal intervals around the shaft portion 120 in the Z direction as viewed from the Z direction, the variation in the height of the protrusion 130 in the Z direction can be easily suppressed, and the welding strength of the protrusion 130 to the inner surface on the -Z side of the side wall 22a can be improved. Furthermore, in the embodiment, compared to a case where the multiple protrusions 130 are arranged at approximately equal intervals or at non-equidistant intervals around the Z direction of the shaft portion 120 as viewed from the Z direction, it is possible to improve the sealing performance between the seat surface 112 and the inner surface on the -Z side of the side wall 22a over a wide range around the Z direction of the shaft portion 120, preferably over the entire range around the Z direction of the shaft portion 120. However, the multiple protrusions 130 may be arranged at approximately equal intervals or at non-equidistant intervals around the Z direction of the shaft portion 120 as viewed from the Z direction.

[0023] 2, in a cross section of approximately the center of weld bolt 100 in a direction perpendicular to the Z direction, each portion located on both sides of shank 120 of projection 130 in a direction perpendicular to the Z direction is approximately triangular. Hereinafter, unless otherwise specified, the cross section of projection 130 means the cross section of the portion on one side of shank 120 of projection 130 in a direction perpendicular to the Z direction.

[0024] With reference to FIG. 3, a cross section of the projection 130 will be described.

[0025] As shown in Fig. 3, the protrusion 130 includes an inner surface 132 and an outer surface 134. In a direction perpendicular to the Z direction, the inner surface 132 is located on the side where the shaft portion 120 is located. In a direction perpendicular to the Z direction, the outer surface 134 is located on the opposite side of the inner surface 132. That is, in a direction perpendicular to the Z direction, the outer surface 134 is located on the opposite side to the shaft portion 120. In Fig. 3, for the purpose of explanation, an imaginary bottom surface 136 of the protrusion 130 is illustrated by a dashed line. The seat surface 112 and the imaginary bottom surface 136 are substantially flush with each other.

[0026] As shown in FIG. 3, the angle α between the inner surface 132 and the virtual bottom surface 136 and the angle β between the outer surface 134 and the virtual bottom surface 136 are different from each other. Therefore, the inner surface 132 and the outer surface 134 have an asymmetric shape. Therefore, compared to the case where the angles α and β are equal to each other, the angle γ between the inner surfaces 132 and 134 can be made smaller by making one of the angles α and β closer to a right angle or an obtuse angle. The smaller the angle γ, the smaller the contact area between the inner surface 132 and the outer surface 134 of the protrusion 130 and the inner surface on the -Z side of the side wall 22a becomes, and the protrusion 130 and the side wall 22a can be more easily welded to each other. Therefore, in the embodiment, compared to the case where the angles α and β are equal to each other, the weld bolt 100 and the upper case 22 can be more easily joined to each other.

[0027] As shown in FIG. 3, the angle α of the inner surface 132 with respect to the imaginary bottom surface 136 is less than the angle β of the outer surface 134 with respect to the imaginary bottom surface 136. Therefore, the tip of the +Z side of the protrusion 130 can be separated from the shaft portion 120 in a direction perpendicular to the Z direction, compared to when the angle β is equal to or less than the angle α. When the welding bolt 100 and the upper case 22 are attached to each other, the shaft portion 120 penetrates through the through hole provided in the side wall 22a in the Z direction. The further the tip of the +Z side of the protrusion 130 and the part to be welded to the inner surface of the -Z side of the side wall 22a are separated from the through hole of the side wall 22a, the less the welding of the protrusion 130 to the inner surface of the -Z side of the side wall 22a is hindered by the shaft portion 120, and the protrusion 130 and the side wall 22a can be easily joined to each other. Therefore, in the embodiment, the welding bolt 100 and the upper case 22 can be easily joined to each other, compared to when the angle β is equal to or less than the angle α. Additionally, in the embodiment, compared to when angle β is equal to or less than angle α, protrusion 130 can be formed more easily, and weld bolt 100 can be made smaller in size more easily. However, angle β may be equal to or less than angle α.

[0028] As shown in FIG. 2 and FIG. 3, the outer surface 134 is shifted toward the side where the shaft portion 120 is located with respect to the outer peripheral surface 116 of the head 110. In molding the head 110 and the protrusion 130, a die located on the +Z side of the head 110 and the protrusion 130 and a die located on the -Z side of the head 110 and the protrusion 130 are pressed against each other in the Z direction. In the embodiment, the outer surface 134 can be pressed by a part of the die located on the +Z side of the head 110 and the protrusion 130, compared to when the outer surface 134 and the outer peripheral surface 116 are flush. Therefore, in the embodiment, the variation in the shape of the protrusion 130 can be suppressed, compared to when the outer surface 134 and the outer peripheral surface 116 are flush. The more the variation in the shape of the protrusion 130 is suppressed, the easier it is to weld the inner surface 132 and the outer surface 134 of the protrusion 130 to the inner surface on the -Z side of the side wall 22a. Therefore, in the embodiment, it is possible to more easily join the weld bolt 100 and the upper case 22 to each other compared to a case in which the outer surface 134 and the outer circumferential surface 116 are flush.

[0029] In one example, the angle α is 57° or more and 63° or less. When the angle α is equal to or more than the lower limit of the above-mentioned range, it is easy to narrow the width of the protrusion 130 in the direction perpendicular to the Z direction. When the angle α is equal to or less than the upper limit of the above-mentioned range, it is possible to make the angle γ sufficiently small while the angle β is close to a right angle or an obtuse angle.

[0030] In one example, the angle β is 72° or more and 78° or less. When the angle β is equal to or more than the lower limit of the above range, it is easy to narrow the width of the protrusion 130 in the direction perpendicular to the Z direction. When the angle β is equal to or less than the upper limit of the above range, the angle β can be close to a right angle or an obtuse angle.

[0031] 4 is a cross-sectional view of a weld bolt 100A according to Modification 1. The weld bolt 100A according to Modification 1 is similar to the weld bolt 100 according to the embodiment, except for the following points.

[0032] The cross section of the protrusion 130A according to the first modification is substantially trapezoidal, so that the tip of the protrusion 130A on the +Z side forms a flat surface that is substantially perpendicular to the Z direction.

[0033] The inner side surface 132 and the outer side surface 134 of the protrusion 130A according to the first modification have an asymmetric shape, similar to the inner side surface 132 and the outer side surface 134 of the protrusion 130 according to the embodiment. The outer side surface 134 of the protrusion 130A according to the first modification is positioned offset toward the side where the shaft portion 120 is positioned with respect to the outer circumferential surface 116 of the head 110, similar to the outer side surface 134 of the protrusion 130 according to the embodiment. Therefore, in the first modification as well, it is possible to easily join the weld bolt 100 and the upper case 22 to each other, similar to the embodiment.

[0034] 5 is a cross-sectional view of a weld bolt 100B according to Modification 2. The weld bolt 100B according to Modification 2 is similar to the weld bolt 100 according to the embodiment, except for the following points.

[0035] When viewed from the Z direction, the weld bolt 100B according to the modified example has a plurality of protrusions 130B arranged in a substantially concentric pattern. In the example shown in Fig. 5, when viewed from the Z direction, two protrusions 130B are arranged in a substantially concentric pattern. However, when viewed from the Z direction, three or more protrusions 130B may be arranged in a substantially concentric pattern.

[0036] The inner side surface 132 and the outer side surface 134 of each protrusion 130B according to Modification 2 have an asymmetric shape, similar to the inner side surface 132 and the outer side surface 134 of the protrusion 130 according to the embodiment. The outer side surface 134 of the protrusion 130B located at the outermost part around the shaft portion 120 in the Z direction according to Modification 2 is shifted toward the side where the shaft portion 120 is located with respect to the outer circumferential surface 116 of the head 110, similar to the outer side surface 134 of the protrusion 130 according to the embodiment. Therefore, in Modification 2 as well, it is possible to easily join the weld bolt 100 and the upper case 22 to each other, similar to the embodiment.

[0037] Although the embodiment and modified examples of the present invention have been described above with reference to the drawings, these are merely examples of the present invention, and various configurations other than those described above can also be adopted.

[0038] For example, in the embodiment, the weld bolt 100 is joined to a module housing 20 that houses a battery module. However, the weld bolt 100 may be joined to a workpiece other than the module housing 20. [Explanation of symbols]

[0039] 10 battery pack, 20 module housing, 22 upper case, 22a side wall, 30 mounting member, 100, 100A, 100B welded bolt, 110 head, 112 seat surface, 114 top surface, 116 outer circumferential surface, 120 shaft portion, 130, 130A, 130B protrusion, 132 inner surface, 134 outer surface, 136 imaginary bottom surface, 200 nut

Claims

1. The head and A shaft portion extending from the head portion; a projection extending from the head and positioned at least partially around the shaft; Equipped with one side surface of the protrusion located on one side where the shaft portion is located and another side surface of the protrusion located on the opposite side to the one side surface are asymmetric in shape, A weld bolt, wherein the other side surface of the projection is positioned offset toward the one side with respect to the outer circumferential surface of the head.

2. 2. The weld bolt of claim 1, wherein an angle of the one side of the projection relative to the head is less than an angle of the other side of the projection relative to the head.

3. The weld bolt according to claim 1 or 2, wherein the projection surrounds the shank.

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