Terminal connection structure and aluminum wire with terminal

Abstract

Disclosed is a terminal connection structure capable of suppressing an increase in contact resistance in terminal connection of different metals between one terminal containing copper or a copper alloy and the other terminal containing aluminum or an aluminum alloy.　A terminal connection structure (10) is for a first terminal (14) and a second terminal (16) fastened by a bolt (18). The first terminal (14) contains copper or a copper alloy, and has a first contact surface (22) that makes contact with a second contact surface (20) of the second terminal (16). The second terminal (16) contains aluminum or an aluminum alloy, and has the second contact surface (20) that makes contact with the first contact surface (22) of the first terminal (14). A plurality of conical protrusions (24) are formed on the first contact surface (22).

Description

Terminal connection structure and aluminum electric wire with terminal

[0001] The present disclosure relates to a terminal connection structure and an aluminum electric wire with a terminal.

[0002] Patent Document 1 discloses a terminal connection structure in which one terminal provided at the end of an electric wire is overlapped with the other terminal held on a terminal block of an on-vehicle component, and the two terminals are connected to each other in a conductive state by fastening them together with a bolt.

[0003] Japanese Patent Application Laid-Open No. 2004-303957

[0004] In recent years, in response to demands for lighter vehicles, there has been an increasing trend toward using aluminum or aluminum alloys for electrical wires and terminals, instead of the conventional copper or copper alloys. This can lead to terminal connections between dissimilar metals, such as one terminal made of aluminum and the other made of copper. In such cases, aluminum is highly reactive and easily forms an oxide film in the atmosphere. Furthermore, the difference in the linear expansion coefficients of the terminals can cause misalignment at the contact interface between the terminals, easily increasing the aluminum oxide film at the contact interface. This can result in increased contact resistance between the terminals.

[0005] Therefore, the present invention discloses a terminal connection structure and an aluminum electric wire with a terminal that can suppress an increase in contact resistance in a terminal connection between dissimilar metals, where one terminal contains copper or a copper alloy and the other terminal contains aluminum or an aluminum alloy.

[0006] The terminal connection structure of the present disclosure is a terminal connection structure of a first terminal and a second terminal fastened by a bolt, wherein the first terminal comprises copper or a copper alloy and has a first contact surface that contacts the second contact surface of the second terminal, the second terminal comprises aluminum or an aluminum alloy and has the second contact surface that contacts the first contact surface of the first terminal, and the first contact surface has a plurality of conical protrusions formed thereon.

[0007] The aluminum electric wire with terminal of the present disclosure is an aluminum electric wire with terminal in which a terminal fitting is connected to the end of an electric wire containing aluminum or an aluminum alloy, the terminal fitting including the first terminal and the second terminal of the terminal connection structure of the present disclosure, the second terminal being connected to the end of the electric wire, and the first terminal being fastened to the second terminal by the bolt using the terminal connection structure of the present disclosure.

[0008] According to the present disclosure, it is possible to provide a terminal connection structure and an aluminum electric wire with a terminal that can suppress an increase in contact resistance in a terminal connection between dissimilar metals, where one terminal contains copper or a copper alloy and the other terminal contains aluminum or an aluminum alloy.

[0009] FIG. 1 is a perspective view showing an aluminum electric wire with a terminal using a terminal connection structure according to a first embodiment. FIG. 2 is an enlarged longitudinal cross-sectional view showing a main portion of an overlapping portion of a first terminal and a second terminal in the aluminum electric wire with terminal shown in FIG. 1, and corresponds to the main portion of the cross-section II-II in FIG. 1. FIG. 3 is a perspective view showing a first terminal constituting the aluminum electric wire with terminal shown in FIG. 1. FIG. 4 is a plan view of the first terminal shown in FIG. 3. FIG. 5 is an explanatory diagram for explaining, in a model, displacement of the first terminal and the second terminal in the aluminum electric wire with terminal shown in FIG. 1 due to thermal expansion and thermal contraction. FIG. 6 is a perspective view showing a first terminal constituting a terminal connection structure according to a second embodiment. FIG. 7 is a plan view of the first terminal shown in FIG. 6. FIG. 8 is a perspective view of a first terminal constituting a terminal connection structure according to a third embodiment. FIG. 9 is a plan view of the first terminal shown in FIG. 8. FIG. 10 is a perspective view of a first terminal constituting a terminal connection structure according to a fourth embodiment. FIG. 11 is a plan view of the first terminal shown in FIG. 10.

[0010] <Description of Embodiments of the Present Disclosure> First, embodiments of the present disclosure will be described. The terminal connection structure of the present disclosure is: (1) a terminal connection structure for a first terminal and a second terminal fastened by a bolt, wherein the first terminal comprises copper or a copper alloy and has a first contact surface that contacts a second contact surface of the second terminal, the second terminal comprises aluminum or an aluminum alloy and has a second contact surface that contacts the first contact surface of the first terminal, and a plurality of conical protrusions are formed on the first contact surface.

[0011] According to the terminal connection structure disclosed herein, a first terminal including copper or a copper alloy and a second terminal including aluminum or an aluminum alloy are connected by bolting. The first terminal has a first contact surface on which a plurality of conical protrusions are formed. Because the first terminal has a higher hardness than the second terminal, the conical protrusions on the first contact surface are likely to penetrate into the second contact surface when the first and second terminals are bolted together. Therefore, if an oxide film is formed on the second contact surface, the conical protrusions can break through the oxide film and contact the second contact surface, ensuring electrical continuity between the first and second terminals. Furthermore, the copper or copper alloy conical protrusions penetrate into the aluminum or aluminum alloy second contact surface, advantageously ensuring a large contact area and reducing initial contact resistance.

[0012] In addition, even when the first terminal and the second terminal are displaced relative to each other due to thermal expansion and contraction caused by the thermal influence of heat when mounted on a vehicle, the tip portion of the conical protrusion of the first terminal easily digs into the second contact surface and follows the second contact surface while remaining in contact with it. This advantageously maintains the contact state between the conical protrusion of the first terminal and the second contact surface, thereby preventing problems such as a decrease in contact point due to sliding at the contact interface between the first terminal and the second terminal caused by thermal expansion and contraction, and the formation of an oxide film due to re-exposure of the contact interface. As described above, the terminal connection structure of this embodiment can prevent an increase in contact resistance in a terminal connection between dissimilar metals, that is, a first terminal containing copper or a copper alloy and a second terminal containing aluminum or an aluminum alloy.

[0013] (2) In the above (1), it is preferable that the first terminal has a first bolt insertion hole through which the bolt is inserted, and the first contact surface is provided surrounding the periphery of the first bolt insertion hole, and the second terminal has a second bolt insertion hole through which the bolt is inserted, and the second contact surface is provided surrounding the periphery of the second bolt insertion hole. The fastening force due to the axial force of the bolt is evenly transmitted to the first and second contact surfaces provided surrounding the periphery of the first and second bolt insertion holes, and the multiple conical protrusions provided on the first contact surface can reliably bite into the second contact surface. This further effectively suppresses an increase in contact resistance between the first terminal and the second terminal.

[0014] (3) In the above (1) or (2), it is preferable that each of the pyramidal protrusions has a quadrangular pyramidal shape. Because each pyramidal protrusion has a quadrangular pyramidal shape, four ridges spaced apart from each other around the apex are formed on the pyramidal protrusion, making it easier for the ridges to penetrate into the second contact surface. Furthermore, the ridges spaced apart from each other around the apex of each pyramidal protrusion penetrate into the second contact surface, allowing the first terminal and the second terminal to effectively accommodate thermal expansion and contraction in all directions. This further effectively suppresses an increase in contact resistance between the first terminal and the second terminal.

[0015] (4) In any one of (1) to (3) above, it is preferable that the plurality of pyramidal protrusions are arranged in a lattice pattern, and each pyramidal protrusion has a square pyramidal shape. Because each pyramidal protrusion has a square pyramidal shape, four ridges can be formed around the apex of the pyramidal protrusion, spaced at 90° intervals. These ridges can uniformly penetrate into the second contact surface and ensure uniform contact between the pyramidal protrusions and the second contact surface. Furthermore, by arranging the plurality of square pyramidal protrusions in a lattice pattern, it is possible to more effectively ensure the contact area between the first terminal and the second terminal and maintain the contact interface, while achieving a balanced response to thermal expansion and contraction in all directions of the first terminal and the second terminal.

[0016] (5) In any one of (1) to (3) above, it is preferable that the plurality of pyramidal protrusions are arranged in a lattice pattern, and each pyramidal protrusion has a quadrangular pyramidal shape with a diamond-shaped base. Because each pyramidal protrusion has a quadrangular pyramidal shape with a diamond-shaped base, pairs of ridge lines of different lengths can be formed at four locations spaced at 90° intervals around the apex of the pyramidal protrusion. By varying the lengths of the ridge lines of the pyramidal protrusions, it is possible to advantageously achieve penetration into the second contact surface by these ridge lines, while imparting anisotropy to the ability of the first and second terminals to respond to displacements due to thermal expansion and contraction. Furthermore, by arranging a plurality of pyramidal protrusions with a quadrangular pyramidal bottom in a lattice pattern, it is possible to more advantageously ensure the contact area between the first and second terminals and maintain the contact interface, while also achieving response to displacements due to thermal expansion and contraction of the first and second terminals in consideration of directionality.

[0017] (6) In the above (2), it is preferable that the plurality of conical protrusions are arranged as a plurality of annular bodies surrounding the first bolt insertion hole, the plurality of annular bodies have diameters that increase sequentially radially outward from the first bolt insertion hole, the same number of the conical protrusions are arranged on each annular body, and the circumferential length of each of the conical protrusions constituting each annular body increases as the diameter of each annular body increases. The amount of displacement of the first terminal and the second terminal due to thermal expansion and contraction increases from the radially inner side to the radially outer side of the first bolt insertion hole. According to this aspect, the circumferential length of each of the conical protrusions arranged as a plurality of annular bodies surrounding the first bolt insertion hole is longer for the conical protrusions arranged on the radially outer annular bodies than for the conical protrusions arranged on the radially inner annular bodies. Therefore, when the first terminal and the second terminal are displaced due to thermal expansion and contraction, the conical protrusions are in contact with the second contact surface over a larger area in the circumferential direction on the radially outer side, and each conical protrusion displaces in accordance with the second contact surface, thereby stably maintaining electrical continuity between the first terminal and the second terminal.Furthermore, in addition to the amount of displacement due to thermal expansion and contraction being small on the radially inner side, the risk of the second contact surface being exposed and the formation of an oxide film can be advantageously reduced by each conical protrusion displacing in accordance with the second contact surface.

[0018] (7) In the above (6), it is preferable that the angular positions of the apexes of the plurality of conical protrusions on each of the annular bodies about the central axis of the first bolt insertion hole are consistent across all of the annular bodies. Since the angular positions of the apexes of the plurality of conical protrusions arranged circumferentially on each of the annular bodies about the central axis of the first bolt insertion hole are consistent across all of the annular bodies, it is possible to advantageously equalize the contact state between the first contact surface and the second contact surface around the first and second bolt insertion holes, thereby preventing the risk of a local increase in electrical resistance.

[0019] (8) In the above (6), it is preferable that the angular positions of the apexes of the plurality of conical protrusions in each of the annular bodies about the central axis of the first bolt insertion hole are different between adjacent annular bodies in the radial direction. By making the angular positions of the apexes of the plurality of conical protrusions arranged in the circumferential direction of each annular body about the central axis of the first bolt insertion hole different between adjacent annular bodies in the radial direction, radial displacement of the first and second contact surfaces due to thermal expansion and contraction of the first and second terminals can be more effectively suppressed.

[0020] The aluminum electric wire with terminal of the present disclosure is (9) an aluminum electric wire with terminal in which a terminal fitting is connected to the end of an electric wire containing aluminum or an aluminum alloy, the terminal fitting including the first terminal and the second terminal in the terminal connection structure described in any one of (1) to (8) above, the second terminal being connected to the end of the electric wire, and the first terminal being fastened to the second terminal by the bolt using the terminal connection structure described in any one of (1) to (8) above.

[0021] According to the aluminum electric wire with terminal of the present disclosure, the first and second terminals constituting the terminal fittings are fastened to each other with bolts using any one of the terminal connection structures (1) to (8) described above. This makes it possible to provide an aluminum electric wire with a terminal that can suppress an increase in contact resistance even when the terminal connection is between dissimilar metals. Furthermore, a second terminal containing aluminum or an aluminum alloy is connected to the end of an electric wire containing aluminum or an aluminum alloy, and a first terminal containing copper or a copper alloy is connected using the terminal connection structure of the present disclosure. Furthermore, the first terminal containing copper or a copper alloy is the part that connects to the external connection terminal of another device. This reduces the risk of an increase in contact resistance when the aluminum electric wire with terminal is connected to an external connection terminal containing copper or a copper alloy. In particular, since the terminal connection between the first and second terminals is completed in the terminal fitting connected to the aluminum electric wire, it is possible to provide an aluminum electric wire that does not require repeated bolt fastening of the aluminum terminal and the copper external connection terminal after each maintenance. This makes it possible to provide an aluminum electric wire with a terminal that can more effectively suppress or eliminate the risk of an increase in contact resistance due to maintenance.

[0022] <Details of the Embodiments of the Present Disclosure> Specific examples of the terminal connection structure and terminal-fitted aluminum electric wire of the present disclosure will be described below with reference to the drawings. Note that the present disclosure is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0023] First Embodiment A terminal connection structure 10 and a terminal-attached aluminum electric wire 12 using the terminal connection structure 10 according to a first embodiment of the present disclosure will be described below with reference to FIGS. 1 to 5 . This terminal-attached aluminum electric wire 12 is provided, for example, in an electric vehicle or a hybrid vehicle. The terminal connection structure 10 constituting the terminal-attached aluminum electric wire 12 is configured to interconnect, for example, a first terminal 14 and a second terminal 16 extending from each side of two on-board devices (not shown). The terminal-attached aluminum electric wire 12 can be positioned in any orientation within the vehicle. However, in the following description, the upper side will be referred to as the upper side in FIG. 2 , the lower side as the lower side in FIG. 2 , the left side as the rear side in a direction perpendicular to the plane of FIG. 2 , the right side as the front side in a direction perpendicular to the plane of FIG. 2 , the front side as the left side in FIG. 2 , and the rear side as the right side in FIG. 2 . Furthermore, in some cases, when multiple identical components are illustrated, only some of the components will be designated by reference numerals, and the reference numerals for the other components will be omitted.

[0024] <Terminal Connection Structure 10> In the terminal connection structure 10 of the first embodiment, a first terminal 14 and a second terminal 16 are connected by fastening them with a bolt 18. The first terminal 14 is made of copper or a copper alloy and has a first contact surface 22 that contacts a second contact surface 20 of the second terminal 16. The second terminal 16 is made of aluminum or an aluminum alloy and has a second contact surface 20 that contacts the first contact surface 22 of the first terminal 14. That is, the first terminal 14 and the second terminal 16 are connected such that the first contact surface 22 and the second contact surface 20 overlap each other. The first contact surface 22 has a plurality of conical protrusions 24 formed thereon. In the first embodiment, the first terminal 14 and the second terminal 16 are connected in the front-rear direction, and the first contact surface 22 and the second contact surface 20 overlap each other in the up-down direction. Specifically, a first contact surface 22 is provided on the upper surface of the rear end of the first terminal 14 , and a second contact surface 20 is provided on the lower surface of the front end of the second terminal 16 .

[0025] <Aluminum Electric Wire with Terminal 12> The aluminum electric wire with terminal 12 of the first embodiment is formed by connecting a terminal fitting 28 to the end of an electric wire 26 made of aluminum or an aluminum alloy. The terminal fitting 28 includes the first terminal 14 and the second terminal 16 of the terminal connection structure 10, and the second terminal 16 is connected to the end of the electric wire 26. The first terminal 14 is fastened to the second terminal 16 with a bolt 18 using the terminal connection structure 10. In the first embodiment, the electric wire 26 is a coated electric wire, and the core wire 30 is covered with an insulating coating 32 made of a synthetic resin or the like. In particular, in the first embodiment, the core wire 30 is a single-core wire made of aluminum or an aluminum alloy, and the core wire 30 and the second terminal 16 are integrally formed. That is, the insulating coating 32 is stripped from the end (front end portion) of the single-core wire made of aluminum or an aluminum alloy, exposing the core wire 30, and the second terminal 16 is configured at the exposed front end portion of the core wire 30.

[0026] <First Terminal 14> As shown in Figures 3 and 4, the first terminal 14 is a strip-shaped member extending in the front-rear direction as a whole, and is made of copper or a copper alloy as described above. The first terminal 14 has a predetermined thickness, width (left-right dimension), and length (front-rear dimension). In the first embodiment, the middle portion of the first terminal 14 in the longitudinal direction is bent in a crank shape, and both ends (front and rear ends) of the first terminal 14 in the longitudinal direction each extend in the horizontal direction (direction perpendicular to the up-down direction), and the middle portion of the first terminal 14 in the longitudinal direction extends in the up-down direction. As a result, the rear end of the first terminal 14 is located higher than the front end.

[0027] More specifically, the rear end of the first terminal 14 is generally rectangular in plan view, and this rear end of the first terminal 14 constitutes the first connection portion 34 to which the second terminal 16 is connected as described above. A first bolt insertion hole 36, through which the bolt 18 is inserted, is formed in the center of the first connection portion 34, penetrating the first connection portion 34 in the thickness direction (vertical direction). The portion of the upper surface of the first connection portion 34 surrounding the first bolt insertion hole 36 constitutes a first contact surface 22 that overlaps and contacts the second terminal 16. In other words, the first contact surface 22 is provided to surround the periphery of the first bolt insertion hole 36.

[0028] The front end of the first terminal 14 is generally rectangular in plan view, and forms an external connection portion 38 to which an external conductive member such as an electric wire or a bus bar (not shown) is connected. A bolt insertion hole 40, through which a bolt (not shown) is inserted, is formed in the center of the external connection portion 38, penetrating the external connection portion 38 in the thickness direction (vertical direction). The bolt inserted into the bolt insertion hole 40 fixes the external conductive member and the first terminal 14 to each other. The first connection portion 34 and the external connection portion 38 are connected by a vertical extension portion 42 that extends vertically.

[0029] <First Contact Surface 22> As described above, the portion of the upper surface of the first connecting portion 34 surrounding the first bolt insertion hole 36 constitutes the first contact surface 22. A conical-protrusion-forming region 44, in which the above-described multiple conical protrusions 24 are formed, is defined in a longitudinally intermediate portion and a transversely intermediate portion of the first contact surface 22. Because the first bolt insertion hole 36 is formed in a central portion of the first connecting portion 34, the first bolt insertion hole 36 is formed in a central portion of the conical-protrusion-forming region 44. In other words, the conical-protrusion-forming region 44 is provided around the first bolt insertion hole 36. In the first embodiment, as described below, the conical protrusions 24 have a square pyramid shape, and the bottom surfaces 46 constituting the conical protrusions 24 are square in plan view. The multiple conical protrusions 24 are aligned in the longitudinal and transverse directions, and in the first embodiment, the conical-protrusion-forming region 44 is substantially square in plan view. At least the first contact surface 22 of the first terminal 14 may be provided with a known plating such as silver plating, and for example, tin plating can be preferably used.

[0030] <Conical Protrusions 24> Each of the conical protrusions 24 has approximately the same shape, and each conical protrusion 24 is a square pyramid. In the first embodiment, the multiple conical protrusions 24 are arranged in a lattice pattern, i.e., aligned in the front-to-back and left-to-right directions, and each conical protrusion 24 is a regular square pyramid. In other words, the bottom surface 46 of each conical protrusion 24 is square in plan view, and the vertex 48 is located above the intersection of the two diagonals of this square. Of the surfaces constituting each conical protrusion 24, the four side surfaces 49 other than the bottom surface 46 are isosceles triangular. Furthermore, as lines constituting these side surfaces 49, four ridgelines 50 extend from the vertex 48 toward the four corners of the bottom surface 46, and each ridgeline 50 is equal in length. Therefore, in plan view, each ridgeline 50 is arranged at equal intervals (every 90 degrees) in the circumferential direction around the central axis of each conical protrusion 24, which passes through the vertex 48 and extends in the up-down direction.

[0031] As shown in FIG. 2 , in the first embodiment, the bottom surface 46 of each conical protrusion 24 is located vertically lower than the portion of the first contact surface 22 other than the conical-protrusion-forming region 44 (the portion of the first contact surface 22 surrounding the conical-protrusion-forming region 44). That is, in the first embodiment, the upper portion of each conical protrusion 24 protrudes above the first contact surface 22. Also, as shown in FIG. 2 , in a vertical cross section passing through the vertex 48 of each conical protrusion 24, two ridgelines 50, 50 intersect at a predetermined angle α. This intersection angle α is not limited, but can be set within the range of 45°≦α≦120°, for example. In the first embodiment, the intersection angle α is 90°. While each vertex 48 may have a somewhat rounded arc shape in the vertical cross section, a pointed shape is preferable. 2 to 4 , among the conical protrusions 24 aligned in the front-rear and left-right directions, a valley portion 51 is formed between adjacent conical protrusions 24, 24, which is concave relative to each conical protrusion 24. In the first embodiment, the bottom surface of this valley portion 51 is an R-curved surface, but it may be a V-shaped inclined surface or a flat surface extending horizontally. The method for forming the first terminal 14 having the conical protrusions 24 shaped as described above is not limited, and it may be formed, for example, by pressing a metal plate made of copper or a copper alloy.

[0032] <Second Terminal 16> As described above, the second terminal 16 is integrally formed with the core wire 30 constituting the electric wire 26 and is configured at the front end portion of a single-core wire made of aluminum or aluminum alloy. The front end portion of the second terminal 16, in particular, is the second connection portion 52 to which the first terminal 14 is connected. The second connection portion 52 is a generally rectangular area in a plan view. A second bolt insertion hole 54, through which the bolt 18 is inserted, is formed in the center of the second connection portion 52, penetrating the second connection portion 52 in the thickness direction (vertical direction). The area around the second bolt insertion hole 54 on the underside of the second connection portion 52 constitutes the second contact surface 20, which overlaps and contacts the first terminal 14. In other words, the second contact surface 20 is provided to surround the second bolt insertion hole 54.

[0033] In the first embodiment, the second contact surface 20 is a flat surface extending horizontally before being overlapped with the first terminal 14. As shown in FIG. 2 , when the first contact surface 22 and the second contact surface 20 are overlapped and the bolt 18 is fastened, the conical protrusions 24 protruding from the first contact surface 22 are engaged with the second contact surface 20, as described below. After the first terminal 14 and the second terminal 16 are fastened, the second contact surface 20 has accommodating recesses 56 having shapes generally corresponding to the conical protrusions 24. Note that FIG. 2 is an enlarged view of the overlapping portion between the first contact surface 22 and the second contact surface 20, particularly the rear portion of the first and second bolt insertion holes 36, 54. Furthermore, when the first terminal 14 and the second terminal 16 are fastened, the conical protrusions 24 are deformed to some extent by the second contact surface 20, so that the accommodating recesses 56 may not have a clearly pointed shape.

[0034] <Bolt 18> The first contact surface 22 of the first terminal 14 and the second contact surface 20 of the second terminal 16 are overlapped with each other, thereby vertically communicating the first bolt insertion hole 36 and the second bolt insertion hole 54. The bolt 18 is inserted into the first bolt insertion hole 36 and the second bolt insertion hole 54 and fastened to the nut 58, thereby fixing the first terminal 14 and the second terminal 16 to each other. The nut 58 is disposed on the underside of the first connecting portion 34 of the first terminal 14. The nut 58 may be fixed to the first connecting portion 34, or may be supported by a separate member (not shown).

[0035] As described above, the first contact surface 22 of the first terminal 14 and the second contact surface 20 of the second terminal 16 are overlapped with each other, and the bolt 18 is inserted into the first and second bolt insertion holes 36, 54 and fastened to the nut 58, thereby forming the terminal connection structure 10 and the aluminum electric wire 12 with a terminal using the terminal connection structure 10.

[0036] <Operations and Effects of Terminal Connection Structure 10 and Terminal-Attached Aluminum Electric Wire 12> The operations and effects of the terminal connection structure 10 and terminal-attached aluminum electric wire 12 will be explained below using a model, particularly Fig. 5 . First, because the second terminal 16 is made of aluminum or an aluminum alloy, an oxide coating 60 is formed on its surface, including the second contact surface 20, before it is fastened to the first terminal 14 by a bolt. Note that Fig. 5 shows each component in a modeled manner, and the thickness dimensions, displacement amounts, etc. of each component may not be accurate. Also, for ease of understanding, the thickness dimension of the oxide coating 60 is exaggerated in Fig. 5 .

[0037] As described above, the first contact surface 22 of the first terminal 14 and the second contact surface 20 of the second terminal 16 are overlapped with each other and fixed together by tightening the bolts 18. Here, each of the pyramidal protrusions 24 protrudes upward from the first contact surface 22. Generally, the copper-based metal constituting the first terminal 14 is harder than the aluminum-based metal constituting the second terminal 16. Therefore, by overlapping and fixing the first contact surface 22 and the second contact surface 20, each of the pyramidal protrusions 24 protruding from the first contact surface 22 breaks through the oxide film 60 on the second contact surface 20 and penetrates into the second connection portion 52. In other words, as each of the pyramidal protrusions 24 penetrates into the second contact surface 20, each of the accommodating recesses 56 having a shape generally corresponding to each of the pyramidal protrusions 24 is formed on the second contact surface 20, and the upper portion of each of the pyramidal protrusions 24 protruding above the first contact surface 22 is accommodated in each of the accommodating recesses 56. As a result, the first terminal 14 and the second terminal 16 come into contact with each other without the oxide film 60 therebetween, and are electrically connected to each other. This state is the "reference state" shown at the top in FIG. 5 .

[0038] Next, assume that the terminal connection structure 10 and the terminal-attached aluminum electric wire 12 are exposed to a high-temperature environment that is hotter than the reference temperature. In a high-temperature environment, the first terminal 14 and the second terminal 16 constituting the terminal connection structure 10 and the terminal-attached aluminum electric wire 12 both expand due to heat. For example, the first connection portion 34 and the second connection portion 52, which are the connection portions between the first terminal 14 and the second terminal 16, expand radially outward from the first bolt insertion hole 36 and the second bolt insertion hole 54 provided in the central portion. Specifically, in FIG. 2 , which shows the rear portions of the first and second bolt insertion holes 36, 54, both the first connection portion 34 and the second connection portion 52 deform so as to extend rearward (to the right in FIG. 2 ).

[0039] In the diagram showing the high-temperature environment in the center of Fig. 5 , the displacement of the first terminal 14 due to the thermal expansion is R1, and the displacement of the second terminal 16 due to the thermal expansion is R2, both of which are indicated by white arrows pointing to the right in Fig. 5. Generally, the aluminum-based metal constituting the second terminal 16 has a larger linear expansion coefficient than the copper-based metal constituting the first terminal 14, and therefore the displacement R2 of the second terminal 16 is larger than the displacement R1 of the first terminal 14. That is, in a high-temperature environment, the accommodating recesses 56 that accommodate the pyramidal protrusions 24 are displaced more significantly, for example, to the right in Fig. 5, relative to the pyramidal protrusions 24. However, because copper-based metals are relatively tough, the pyramidal protrusions 24 are able to deform in accordance with the displacement of the accommodating recesses 56 without breaking. This allows each conical protrusion 24 to remain embedded in the second connection portion 52 and accommodated in each accommodation recess 56 even in high temperature environments, thereby maintaining electrical continuity between the first terminal 14 and the second terminal 16.

[0040] Additionally, due to the heat, the first terminal 14 and the second terminal 16 also expand in the vertical direction, i.e., the thickness direction. The upward displacement of the first terminal 14 due to this thermal expansion is A1, and the downward displacement of the second terminal 16 due to this thermal expansion is A2, as indicated by white arrows in FIG. 5 . Because the displacement due to thermal expansion moves the first terminal 14 and the second terminal 16 closer to each other, the conical protrusions 24 penetrate more deeply into the second connecting portion 52 in a high-temperature environment than in a reference environment. This also allows the first terminal 14 and the second terminal 16 to maintain electrical continuity in a high-temperature environment.

[0041] Furthermore, assuming that the terminal connection structure 10 and the terminal-attached aluminum electric wire 12 are exposed to a low-temperature environment that is lower than the reference temperature, the bottom of Figure 5 shows a diagram labeled "Low-Temperature Environment." In a low-temperature environment, the first terminal 14 and the second terminal 16 constituting the terminal connection structure 10 and the terminal-attached aluminum electric wire 12 both shrink due to heat. In the diagram for "Low-Temperature Environment," the displacement of the first terminal 14 due to thermal shrinkage is indicated by F1, and the displacement of the second terminal 16 due to thermal shrinkage is indicated by white arrows pointing leftward in Figure 5. As described above, because aluminum-based metals generally have a higher linear expansion coefficient than copper-based metals, the displacement F2 of the second terminal 16 is greater than the displacement F1 of the first terminal 14. That is, in a low-temperature environment, the accommodating recesses 56 that accommodate the pyramidal protrusions 24 are displaced more significantly, for example, to the left in Figure 5, relative to the pyramidal protrusions 24. However, the pyramidal protrusions 24 are able to deform in accordance with the displacement of the accommodating recesses 56 without breaking. This allows each conical protrusion 24 to remain embedded in the second connection portion 52 and accommodated in each accommodation recess 56 even in low-temperature environments, thereby maintaining electrical continuity between the first terminal 14 and the second terminal 16.

[0042] In addition, due to the heat, the first terminal 14 and the second terminal 16 also shrink in the vertical direction, i.e., the thickness direction. The downward displacement of the first terminal 14 due to this thermal contraction is S1, and the upward displacement of the second terminal 16 due to this thermal contraction is S2, as indicated by white arrows in FIG. 5 . The displacement due to thermal contraction is a displacement in the direction in which the first terminal 14 and the second terminal 16 move away from each other, but at the reference time, each of the pyramidal protrusions 24 is embedded in the second connecting portion 52 to some extent. Furthermore, because the first terminal 14 and the second terminal 16 are fastened by the bolt 18, there is no significant displacement in the direction in which they move away from each other. Even if the pyramidal protrusions 24 and the second connecting portion 52 move slightly away from each other in a low-temperature environment, the embedding of each of the pyramidal protrusions 24 into the second connecting portion 52 is maintained. This also allows electrical continuity between the first terminal 14 and the second terminal 16 to be maintained in a low-temperature environment.

[0043] According to the terminal connection structure 10 configured as described above, when connecting the first terminal 14 containing copper or a copper alloy and the second terminal 16 containing aluminum or aluminum, the pyramidal protrusions 24 protruding from the first contact surface 22 of the first terminal 14 are adapted to dig into the second contact surface 20 of the second terminal 16. This allows the pyramidal protrusions 24 to break through the oxide film 60 formed on the second contact surface 20, thereby establishing electrical continuity between the first terminal 14 and the second terminal 16. Furthermore, even when the first terminal 14 and the second terminal 16 expand or contract due to temperature changes, the pyramidal protrusions 24 digging into the second contact surface 20 deform in accordance with the displacement of the second contact surface 20, thereby maintaining the digging-in state of the pyramidal protrusions 24 and enabling stable electrical continuity between the first terminal 14 and the second terminal 16.

[0044] The first terminal 14 has a first bolt insertion hole 36, and a first contact surface 22 is provided surrounding the periphery of the first bolt insertion hole 36. The second terminal 16 has a second bolt insertion hole 54, and a second contact surface 20 is provided surrounding the periphery of the second bolt insertion hole 54. As a result, when the bolt 18 is inserted into the first and second bolt insertion holes 36, 54 and fastened, the axial force of the bolt 18 presses the first and second contact surfaces 22, 20 in directions approaching each other, allowing each conical protrusion 24 to bite into the second contact surface 20 more reliably.

[0045] Each pyramidal protrusion 24 has a square pyramidal shape, and in the first embodiment, the pyramidal protrusions 24 are regular square pyramidal shapes and arranged in a lattice pattern. Because each pyramidal protrusion 24 has a square pyramidal shape, adjacent side surfaces 49 of each pyramidal protrusion 24 intersect at a relatively small angle compared to, for example, a pyramidal protrusion whose base is polygonal with more corners (e.g., a pentagonal pyramid, a hexagonal pyramid, etc.), and the ridges 50 located between the adjacent side surfaces 49, 49 can be utilized to stably insert each pyramidal protrusion 24 into the second contact surface 20. In particular, because each pyramidal protrusion 24 has a square pyramidal shape and is arranged in a lattice pattern, it can deform in both directions in response to displacements caused by thermal expansion and contraction, thereby more stably maintaining electrical continuity between the first terminal 14 and the second terminal 16.

[0046] Furthermore, in each conical protrusion 24, two ridge lines 50, 50 intersect at a 90-degree angle in a vertical cross section passing through the vertex 48. That is, if the intersection angle of the two ridge lines is too small, there is a risk of the protrusion breaking when pressed against the second terminal, and if the intersection angle is too large, there is a risk of the protrusion not being able to fully penetrate into the second terminal. In contrast, by setting the intersection angle of the two ridge lines 50, 50 in the vertical cross section to 90 degrees, it is possible to ensure the strength of the conical protrusion while also being able to fully penetrate into the second terminal 16.

[0047] Furthermore, in the aluminum electric wire with terminal 12 configured as described above, a terminal fitting 28 is connected to the end of an electric wire 26 made of aluminum or an aluminum alloy, and this terminal fitting 28 includes the first terminal 14 and the second terminal 16 connected by the terminal connection structure 10. That is, in the aluminum electric wire with terminal 12, the first terminal 14 and the second terminal 16 are made of dissimilar metals, but problems such as deterioration of electrical conductivity due to differences in their linear expansion coefficients can be resolved, and weight can also be reduced. In particular, in the aluminum electric wire with terminal 12, the front end of the first terminal 14 serves as the external connection portion 38, preventing unnecessary release of the bolt fastening between the first terminal 14 and the second terminal 16. Therefore, deformation and wear of each pyramidal protrusion 24 can be suppressed, and electrical continuity between the first terminal 14 and the second terminal 16 can be maintained for a long period of time.

[0048] Second Embodiment Next, a first terminal 72 constituting a terminal connection structure 70 according to a second embodiment of the present disclosure will be described with reference to Figures 6 and 7. Note that the second terminal constituting the terminal connection structure 70 and the structure of the terminal-attached aluminum electric wire using the terminal connection structure 70 are the same as those of the first embodiment, and therefore will not be shown in the drawings. The basic structure of the first terminal 72 is the same as that of the first embodiment, but the shape of the conical protrusion 74 differs from that of the first embodiment. In the following embodiments, the same members and parts as those of the first embodiment are denoted by the same reference numerals in the drawings, and detailed description thereof will be omitted.

[0049] <Conical Protrusions 74> In the second embodiment, the conical protrusions 74 are arranged in a lattice pattern, and each conical protrusion 74 has a quadrangular pyramid shape with a diamond-shaped base 76. In other words, the four sides constituting the base 76 of each conical protrusion 74 are all equal in length, and the vertex 48 is located above the intersection of the long diagonal and the short diagonal. Therefore, in the second embodiment, each conical protrusion 74 has a long ridge 78a and a short ridge 78b as ridge lines 78 extending from the vertex 48. In a vertical cross section of each conical protrusion 74, the intersection angle between the ridge lines 78b, 78b, may be, for example, 90 degrees. Furthermore, in a vertical cross section of each conical protrusion 74, the intersection angle between the ridge lines 78a, 78a, 78a may be, for example, greater than 90 degrees. The intersection angle between the ridge lines 78 a, 78 a and the intersection angle between the ridge lines 78 b, 78 b are not limited. Furthermore, in the second embodiment, the bottom surfaces of the valleys 51 between the conical protrusions 74 are V-shaped inclined surfaces, but similar to the first embodiment, the bottom surfaces of the valleys may be rounded curved surfaces.

[0050] In the enlarged view of FIG. 7 , the vertices 48 are indicated by black circles, and a straight line L passing through each vertex 48 (black circle) and extending in the front-rear direction is indicated by a dashed line. As can be seen from FIG. 7 , the multiple straight lines L passing through each vertex 48 in the front-rear direction extend parallel to each other at approximately equal intervals in the left-right direction. Focusing on one vertex 48 and the straight line L passing through that vertex 48, it can be seen that straight lines L passing through vertices 48 on both sides in the front-rear direction are located between the straight lines L passing through adjacent vertices 48 in the left-right direction. In other words, the number of straight lines L can be increased compared to the first embodiment (see FIG. 4 ) in which the bottom surface 46 is square and aligned in the front-rear and left-right directions. In other words, the conical protrusions 74 can come into contact with the second contact surface 20 at more locations in the left-right direction than in the first embodiment. Furthermore, making the bottom surface shape of the pyramidal protrusion diamond-shaped does not necessarily increase the number of contact points in the left-right direction (the number of straight lines L); the number of contact points in the left-right direction changes depending on the length of the sides that make up the bottom surface and the arrangement of each pyramidal protrusion.

[0051] The terminal connection structure 70 having the first terminal 72 of the second embodiment configured as described above can also achieve the same effects as those of the first embodiment, since the only difference compared to the first embodiment is the shape of the bottom surface 76 of each pyramidal protrusion 74. Furthermore, when the bottom surface 76 is diamond-shaped as in the second embodiment, the long ridge 78a and short ridge 78b of each pyramidal protrusion 74 can be provided, which can provide an effect particularly in a specific direction in terms of displacement of the second terminal 16 due to thermal expansion or thermal contraction. Alternatively, as described above, the number of contact points between each pyramidal protrusion 74 and the second contact surface 20 can be increased in a specific direction (the left-right direction in the second embodiment), thereby preventing relative displacement between the first terminal 14 and the second terminal 16 due to, for example, forward-backward displacement due to thermal expansion or thermal contraction, thereby stably maintaining electrical continuity.

[0052] Third Embodiment Next, a first terminal 82 constituting a terminal connection structure 80 according to a third embodiment of the present disclosure will be described with reference to Figures 8 and 9. Note that the second terminal constituting the terminal connection structure 80 and the structure of the terminal-attached aluminum electric wire using the terminal connection structure 80 are the same as those of the first embodiment, and therefore are not shown in the figures. The basic structure of the first terminal 82 is the same as that of the first embodiment, but the shape and arrangement of the conical protrusions 84 differ from those of the first embodiment.

[0053] <Conical protrusions 84> The conical protrusions 84 of the third embodiment are arranged to form a plurality of annular bodies 86 around the first bolt insertion hole 36. In other words, the plurality of conical protrusions 84 are arranged in an annular shape surrounding the first bolt insertion hole 36, and a plurality of annular bodies 86 each composed of the plurality of conical protrusions 84 are provided. As a result, each annular body 86 has an apex 48 of each conical protrusion 84, and in each annular body 86, these apexes 48 are located on the same circumference. That is, in the third embodiment, a conical-protrusion forming region 87 in which the conical protrusions 84 are formed is annular, and the conical-protrusion forming region 87 is provided on the upper surface of the first connection portion 34 around the first bolt insertion hole 36.

[0054] Specifically, in the third embodiment, five annular bodies 86 (first annular body 86a to fifth annular body 86e) are provided, and the diameters of the annular bodies 86a to 86e increase sequentially radially outward from the first bolt insertion hole 36. The same number of conical protrusions 84 are arranged on each of the annular bodies 86a to 86e, and the circumferential length of each of the conical protrusions 84 constituting each of the annular bodies 86a to 86e increases as the diameter of the annular body 86a to 86e increases. In particular, in the third embodiment, the angular positions of the vertices 48 of the conical protrusions 84 constituting each of the annular bodies 86a to 86e about the central axis of the first bolt insertion hole 36 are consistent among the annular bodies 86a to 86e.

[0055] More specifically, multiple conical protrusions 84 are arranged in a circumferential direction to form each annular body 86a-86e. In short, the bottom surface 88 of each conical protrusion 84 has a short inner arc 90a and a long outer arc 90b in a plan view. Because each annular body 86a-86e is arranged without any gaps in the radial direction, the long outer arc 90b of a conical protrusion 84 constituting a given annular body 86 is also the short inner arc 90a of a conical protrusion 84 constituting the annular body 86 located outside it. In each conical protrusion 84, the short inner arc 90a and the short outer arc 90b are connected at their circumferential ends by radially extending sides 92. Each vertex 48 is located above the center of the bottom surface 88, and each side surface 49 constituting each conical protrusion 84 is generally triangular in a plan view. In each of the conical protrusions 84 of the third embodiment, the intersection angle of each ridge line can be set to 90 degrees in a vertical cross section cut along a plane passing through the first bolt insertion hole 36 and each vertex 48 .

[0056] In addition, the positions of the vertices 48 of the conical protrusions 84 constituting each of the annular bodies 86a to 86e are located, in a plan view, on a straight line that passes through the center of the first bolt insertion hole 36 and extends radially. That is, in each of the annular bodies 86a to 86e, the conical protrusions 84 constituting the outermost annular body 86 are located on the outer peripheral side of one conical protrusion 84, so that five conical protrusions 84 are arranged radially side by side at specific positions on the circumference. Furthermore, the vertices 48 of these five conical protrusions 84 are located on the same straight line that passes through the center of the first bolt insertion hole 36 and extends radially.

[0057] The terminal connection structure 80 having the first terminal 82 of the third embodiment configured as described above can also achieve the same effects as the first embodiment, since the only differences compared to the first embodiment are the shape of the bottom surface 88 of each conical protrusion 84 and the arrangement of each conical protrusion 84. Furthermore, as described above, during thermal expansion in a high-temperature environment and thermal contraction in a low-temperature environment, the first terminal 82 and the second terminal 16 are displaced radially about the first and second bolt insertion holes 36, 54. In particular, the amount of displacement due to this displacement is greater on the radially outer side than on the radially inner side. In contrast, in the third embodiment, the circumferential length of each conical protrusion 84 on the radially outer side is increased, so that even if the second terminal 16 is displaced relatively significantly, the conical protrusions 84 can deform accordingly, thereby stably maintaining electrical continuity between the first terminal 82 and the second terminal 16. Furthermore, since the amount of displacement of the second terminal 16 is relatively small on the radially inner side, gaps are less likely to form between each conical protrusion 84 and the second terminal 16 (each accommodating recess 56), which also makes it possible to stably maintain the conductive state between the first terminal 82 and the second terminal 16.

[0058] Furthermore, as described above, displacement of the first terminal 82 and the second terminal 16 occurs in the radial direction around the first and second bolt insertion holes 36, 54, and therefore, by aligning the apexes 48 of each of the conical protrusions 84 in the radial direction, it is possible to stably cause each of the conical protrusions 84 to deform in response to the displacement of the second terminal 16. This makes it possible to maintain the electrical continuity between the first terminal 82 and the second terminal 16 even more stably.

[0059] Fourth Embodiment Next, a first terminal 102 constituting a terminal connection structure 100 according to a fourth embodiment of the present disclosure will be described with reference to Figures 10 and 11. Note that the structures of the second terminal constituting the terminal connection structure 100 and the aluminum electric wire with a terminal using the terminal connection structure 10 are the same as those of the first embodiment, and therefore are not shown in the figures. In the fourth embodiment, conical protrusions 84 having the same shape as those of the third embodiment are employed, but the arrangement of the conical protrusions 84 differs from that of the third embodiment.

[0060] In the fourth embodiment as well, first to fifth annular bodies 86a to 86e are configured by the respective conical protrusions 84. The angular positions of the vertices 48 of the respective conical protrusions 84 of the annular bodies 86a to 86e around the central axis of the first bolt insertion hole 36 are different between adjacent annular bodies 86 in the radial direction.

[0061] In the enlarged view of FIG. 11 , the vertices 48 are indicated by black circles, and a straight line L' that passes through the vertices 48 (black circles) and extends radially of the first bolt insertion hole 36 is indicated by a dashed line. As can be seen from FIG. 11 , the multiple straight lines L' that pass through each vertex 48 and extend radially extend parallel to one another at approximately equal intervals in the circumferential direction. Focusing on one vertex 48 and the straight line L' that passes through that vertex 48, it can be seen that straight lines L' that pass through the vertices 48 located on both the inner and outer radial sides are located between the straight lines L' that pass through the vertices 48 adjacent to each other in the circumferential direction. In other words, compared to the third embodiment (see FIG. 9 ) in which the vertices 48 of the conical protrusions 84 that constitute each annular body 86 a to 86 e are aligned radially, the number of straight lines L' can be increased. In other words, the conical protrusions 84 can come into contact with the second contact surface 20 at more locations in the circumferential direction than in the third embodiment. In particular, in embodiment 4, each vertex 48 of the conical protrusions 84 that constitute the first, third, and fifth annular bodies 86a, 86c, and 86e is located on a straight line L' that extends radially, and each vertex 48 of the conical protrusions 84 that constitute the second and fourth annular bodies 86b, 86d is located on another straight line L' that extends radially.

[0062] The terminal connection structure 100 having the first terminal 102 of the fourth embodiment configured as described above can also achieve the same effects as those of the first embodiment, since the only difference compared to the third embodiment is the arrangement of the conical protrusions 84. Furthermore, as described above, compared to the third embodiment, the number of contact points between the conical protrusions 84 and the second contact surface 20 in the circumferential direction can be increased, and relative displacement between the first terminal 102 and the second terminal 16 can be prevented in the event of radial displacement due to, for example, thermal expansion or thermal contraction, thereby stably maintaining a conductive state.

[0063] <Modifications> Although Embodiments 1 to 4 have been described above in detail as specific examples of the present disclosure, the present disclosure is not limited to these specific descriptions. Modifications, improvements, etc. within the scope of achieving the object of the present disclosure are included in the present disclosure. For example, the following modifications of the embodiments are also included in the technical scope of the present disclosure.

[0064] (1) In the above embodiment, the first bolt insertion hole 36 was formed in the central portion of the conical protrusion forming region 44, 87, but the first bolt insertion hole may be formed at a position outside the conical protrusion forming region.

[0065] (2) The shape of each conical protrusion is not limited. The polygonal pyramidal shape of the first and second embodiments is not limited to a quadrangular pyramidal shape. It may also be a pyramidal shape with a base that has five or more sides. Alternatively, it may be a conical shape, or the base shape of each conical protrusion may be a mixture or combination of a polygonal shape and a circular shape (including an ellipse, an oval, a semicircle, etc.). The shapes of the conical protrusions do not all need to be the same. For example, the shapes of the conical protrusions on the radially inner side and the radially outer side may be different, taking into account the amount of displacement of the second terminal due to thermal expansion or contraction. Furthermore, as described above, the bottom surfaces of the valleys between the conical protrusions may be curved, V-shaped, or flat, extending horizontally. Furthermore, appropriate gaps may be provided between the conical protrusions depending on the size and shape of each conical protrusion.

[0066] (3) In the above embodiment, the core wire 30 of the electric wire 26 and the second terminal 16 are integrally formed. However, they may be formed as separate bodies and electrically connected to each other.

[0067] (4) In the above embodiment, the first terminals 14, 72, 82, 102 have a vertical extension portion 42 in the middle of their length and are bent like a crank. However, this is not limited to this form, and the first terminals may simply be shaped to extend in the front-to-rear direction.

[0068] (5) In the first embodiment, the upper portions of the conical protrusions 24 protrude above the first contact surface 22, and the second contact surface 20 overlaps the annular portion of the first contact surface 22 surrounding the conical-protrusion-forming region 44. However, this is not limited to this configuration. For example, if the left-right dimension of the second contact surface is smaller than the left-right dimension of the conical-protrusion-forming region in a plan view, and the conical-protrusion-forming region extends to the end (rear end) of the first connecting portion, or if substantially the entire first contact surface (the upper surface of the first connecting portion) is the conical-protrusion-forming region and each conical protrusion is provided therein, each conical protrusion does not need to protrude above the first contact surface. Note that in such cases, the apexes of each conical protrusion can be considered to constitute the first contact surface. The same applies to the second to fourth embodiments.

[0069] REFERENCE SIGNS LIST 10 Terminal connection structure (first embodiment) 12 Aluminum electric wire with terminal 14 First terminal 16 Second terminal 18 Bolt 20 Second contact surface 22 First contact surface 24 Conical protrusion 26 Electric wire 28 Terminal fitting 30 Core wire 32 Insulating coating 34 First connection portion 36 First bolt insertion hole 38 External connection portion 40 Bolt insertion hole 42 Vertical extension portion 44 Conical protrusion forming region 46 Bottom surface 48 Apex 49 Side surface 50 Ridge line 51 Valley portion 52 Second connection portion 54 Second bolt insertion hole 56 Receiving recess 58 Nut 60 Oxide coating 70 Terminal connection structure (second embodiment) 72 First terminal 74 Conical protrusion 76 Bottom surface 78 Ridge line 78a Long ridge line 78b Short ridge line 80 Terminal connection structure (third embodiment) 82 First terminal 84 Conical protrusion 86 Annular body 86a to 86e First to fifth annular bodies 87 Conical protrusion forming region 88 Bottom surface 90a Short arc on inner periphery 90b Long arc on outer periphery 92 Side portion extending in radial direction 100 Terminal connection structure (fourth embodiment) 102 First terminal A1 Amount of upward displacement of first terminal due to thermal expansion A2 Amount of downward displacement of second terminal due to thermal expansion F1 Amount of displacement of first terminal due to thermal contraction F2 Amount of displacement of second terminal due to thermal contraction R1 Amount of displacement of first terminal due to thermal expansion R2 Amount of displacement of second terminal due to thermal expansion S1 Amount of downward displacement of first terminal due to thermal contraction S2 Amount of upward displacement of second terminal due to thermal contraction L Straight line L' passing through the apex of the conical protrusion and extending in the front-to-rear direction A straight line passing through the apex of the conical protrusion and extending in the radial direction of the first bolt insertion hole α is the intersection angle of the ridge line in the vertical cross section of the conical protrusion

Claims

1. A terminal connection structure for a first terminal and a second terminal fastened by a bolt, wherein the first terminal comprises copper or a copper alloy and has a first contact surface that contacts the second contact surface of the second terminal, and the second terminal comprises aluminum or an aluminum alloy and has a second contact surface that contacts the first contact surface of the first terminal, and a plurality of conical protrusions are formed on the first contact surface.

2. A terminal connection structure as described in claim 1, wherein the first terminal has a first bolt insertion hole through which the bolt is inserted, and the first contact surface is provided surrounding the periphery of the first bolt insertion hole, and the second terminal has a second bolt insertion hole through which the bolt is inserted, and the second contact surface is provided surrounding the periphery of the second bolt insertion hole.

3. A terminal connection structure according to claim 1 or claim 2, wherein each of said pyramidal protrusions has a square pyramidal shape.

4. A terminal connection structure according to claim 1 or 2, wherein the plurality of pyramidal protrusions are arranged in a lattice pattern, and each pyramidal protrusion has a square pyramidal shape.

5. A terminal connection structure according to claim 1 or 2, wherein the plurality of conical protrusions are arranged in a lattice pattern, and each conical protrusion has a quadrangular pyramid shape with a diamond-shaped base.

6. A terminal connection structure as described in claim 2, wherein the plurality of conical protrusions are arranged as a plurality of annular bodies surrounding the first bolt insertion hole, the diameters of the plurality of annular bodies successively increasing radially outward from the first bolt insertion hole, the same number of conical protrusions are arranged on each annular body, and the circumferential length of each of the conical protrusions constituting each annular body increases as the diameter of each annular body increases.

7. A terminal connection structure as set forth in claim 6, wherein the angular positions of the apexes of the plurality of conical protrusions in each of the annular bodies about the central axis of the first bolt insertion hole are consistent for all of the annular bodies.

8. A terminal connection structure as described in claim 6, wherein the angular positions of the apexes of the multiple conical protrusions in each annular body around the central axis of the first bolt insertion hole are different between adjacent annular bodies in the radial direction.

9. An aluminum electric wire with terminal, in which a terminal fitting is connected to the end of an electric wire containing aluminum or an aluminum alloy, wherein the terminal fitting is configured to include the first terminal and the second terminal in the terminal connection structure described in claim 1 or claim 2, the second terminal is connected to the end of the electric wire, and the first terminal is fastened to the second terminal by the bolt using the terminal connection structure described in claim 1 or claim 2.

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