Fuse unit

Abstract

This fuse unit (1) comprises: a bus bar (3) that acts as a conductor and in which a section to be cut (3b) is set; a case body (2) that supports two points sandwiching the section to be cut; a cutting section (4) that is disposed in a first space (6) that is an internal space of the case body and is formed on one side with respect to the bus bar, the cutting section acting as an insulator; and a reconnection section (5) that is disposed in a second space (7) that is an internal space of the case body and is formed on the side of the bus bar opposite to the first space, the reconnection section acting as a conductor, wherein the cutting section has a tip section (4c) that cuts the bus bar into a first portion (14) and a second portion (15) at the section to be cut and is able to move into the second space, and the reconnection section has a first connection section (5b) that comes into contact with the first portion and a second connection section (5c) that comes into contact with the second portion.

Description

fuse unit

[0001] The present invention relates to the technical field of fuse units.

[0002] Fuse units are known that cut off electrical connections to ensure safety in the event of an abnormality, etc. For example, in vehicles equipped with high-voltage onboard batteries, fuse units are used to cut off power supply from the onboard battery in the event of an accident.

[0003] Japanese Patent Application Laid-Open No. 2003-144993 discloses a configuration in which a fusible element of a fusible element unit melts to interrupt an electric circuit, thereby protecting various electric components and electric circuits.

[0004] Japanese Patent Application Laid-Open No. 2022-45414

[0005] However, after an electrical connection has been cut off by a fuse unit, it may be desirable to temporarily restore the electrical connection. For example, in a vehicle, a fuse unit functions to cut off the power supply from the vehicle battery in the event of an accident, ensuring the safety of the occupants. However, there are cases where it is dangerous to leave the damaged vehicle at the accident scene, and it is preferable to move the damaged vehicle to a safe location before a tow truck arrives. In such cases, it is desirable to temporarily restore the electrical connection that was cut off by the fuse unit.

[0006] The present invention has been made in view of the above-mentioned problems, and has an object to provide a fuse unit that is capable of releasing and restoring electrical connection with a simple configuration.

[0007] According to one aspect of the present invention, there is provided a fuse unit comprising: a bus bar having a conductive cut portion; a case body supporting the cut portion at two points on either side; a cutting portion disposed in a first space formed within the internal space of the case body on one side of the bus bar and made of an insulator; and a reconnecting portion disposed in a second space formed within the internal space of the case body on the opposite side of the bus bar from the first space and made of a conductive material, wherein the cutting portion has a tip end that cuts the bus bar into a first portion and a second portion at the cut portion and is movable into the second space, and the reconnecting portion has a first connecting portion that contacts the first portion and a second connecting portion that contacts the second portion, such that after the cutting portion cuts the bus bar and electrically disconnects the first portion from the second portion, the reconnecting portion reestablishes electrical connection between the first portion and the second portion.

[0008] According to the fuse unit of the present invention, it is possible to release and restore electrical connection with a simple configuration.

[0009] FIG. 1 is a schematic cross-sectional view showing an example of the configuration of a fuse unit according to an embodiment of the present invention; FIG. 2 is a schematic perspective view showing an enlarged view of a cut tip of the fuse unit and a bus bar; FIG. 3 is a schematic view showing a state in which the bus bar is separated into a first part and a second part; FIG. 4 is a schematic cross-sectional view showing an example of a cut state of the fuse unit; FIG. 5 is a schematic cross-sectional view showing another example of a cut state of the fuse unit, showing a state in which both tip parts of the first part and the second part are in contact with an insulating part; FIG. 6 is a schematic cross-sectional view showing an example of a reconnected state of the fuse unit; FIG. 7 is a schematic cross-sectional view showing an example of a fuse unit according to a first modified example; FIG. 8 is a schematic cross-sectional view showing an example of a normal state of the fuse unit according to a second modified example; FIG. 9 is a schematic cross-sectional view showing an example of a reconnected state of the fuse unit according to a third modified example.

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A fuse unit 1 according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

[0011] 1. Configuration of the Fuse Unit An example configuration of a fuse unit 1 of the present invention is shown in Fig. 1. The fuse unit 1 is used to protect components located downstream and reduce impact on personnel by cutting off electrical connections upstream closer to the power source. For example, in an application to a vehicle, the fuse unit 1 may be provided near the vehicle battery or near an ECU (Electronic Control Unit) to be protected.

[0012] The fuse unit 1 includes a case body 2 having a space formed therein, a bus bar 3 formed of a conductor, a cutting portion 4 for cutting the bus bar 3, and a reconnection portion 5 for restoring the electrical connection after the bus bar 3 has been cut.

[0013] The case body 2 is made of an insulating material, and the bus bar 3 is disposed approximately in the center of the internal space of the case body 2. Inside the case body 2, there are a first space 6 formed on one side of the bus bar 3, and a second space 7 formed on the opposite side of the first space 6 with respect to the bus bar 3.

[0014] In the following description, the direction in which the first space 6 and the second space 7 are aligned will be referred to as the up-down direction D1. A plane perpendicular to the up-down direction D1 will be referred to as the horizontal plane. However, the horizontal plane in the description does not necessarily need to be perpendicular to the direction of gravity when the fuse unit 1 is actually installed.

[0015] Furthermore, the direction in which the bus bar 3 extends inside the fuse unit 1 is referred to as the left-right direction D2, and the direction perpendicular to the up-down direction D1 and the left-right direction D2 is referred to as the front-rear direction D3. Of course, the left-right direction D2 and the front-rear direction D3 are used for convenience of explanation, and the mounting direction of the fuse unit 1 is not limited to these directions.

[0016] The first space 6 and the second space 7 may be cylindrical spaces, cubic spaces, or other spaces. In the following description, an example in which the first space 6 and the second space 7 are each cylindrical spaces will be given.

[0017] The cutting portion 4 is disposed in the first space 6. The cutting portion 4 includes a large diameter portion 4a having substantially the same size as the cross section of the first space 6, a small diameter portion 4b that continues downward from the large diameter portion 4a, and a cutting tip portion 4c that protrudes downward from the center of the small diameter portion 4b.

[0018] As shown in FIG. 2, the cutting tip 4c has a triangular prism shape with its axial direction aligned with the front-rear direction D3, and its width in the left-right direction D2 decreases as it goes downward.

[0019] The case body 2 has a support protrusion 2a formed on the inner peripheral surface of the first space 6, approximately near the center in the up-down direction D1.

[0020] A plurality of support protrusions 2a may be provided at intervals in the circumferential direction on the inner surface of the first space 6, or may be provided in the form of a ring without interruption in the circumferential direction.

[0021] The cutting portion 4 is maintained in a position midway in the vertical direction D1 in the first space 6 by the step at the boundary between the large diameter portion 4a and the small diameter portion 4b being supported from below by the support protrusion 2a.

[0022] The first space 6 is divided into an upper space and a lower space when the cutting part 4 is disposed, and a mechanism for pushing the cutting part 4 downward in an emergency is disposed in the upper space. In this example, an ignition wire 8 and an explosive 9 disposed at the tip of the ignition wire 8 are disposed in the space above the cutting part 4.

[0023] The reconnection portion 5 is disposed in the second space 7. The reconnection portion 5 is formed as a conductor and includes a cylindrical base portion 5a having approximately the same size as the cross section of the second space 7, a first connection portion 5b protruding upward from one end of the base portion 5a in the left-right direction D2, and a second connection portion 5c protruding upward from the other end of the base portion 5a in the left-right direction D2. The vertical cross section of the reconnection portion 5 is approximately U-shaped.

[0024] The second space 7 is divided into an upper space and a lower space when the reconnection part 5 is disposed, and a spring member 10 is disposed in the lower space to urge the reconnection part 5 upward. The spring member 10 is, for example, a compression coil spring.

[0025] The reconnection portion 5 is provided as a flange portion 5d that protrudes outward at the boundary portion between the base portion 5a and the first and second connection portions 5b and 5c. The case body 2 is formed with a movement restriction portion 2b that is convex inward, on the inner peripheral surface of the second space 7, approximately near the center in the up-down direction D1.

[0026] The reconnection part 5 disposed in the second space 7 is restricted from further upward movement by the engagement of the flange part 5d with the movement restricting part 2b.

[0027] The inner surface of the first connection portion 5b of the reconnection portion 5, the inner surface of the second connection portion 5c, and the upper surface of the base portion 5a between the first connection portion 5b and the second connection portion 5c are formed as a recess 5e.

[0028] An insulating portion 11 made of an insulating material is attached to the surface of the recess 5e.

[0029] A mechanism for pushing up the reconnection part 5 is disposed in the lower space of the second space 7. In this example, an ignition wire 12 and explosives 13 disposed at the tip of the ignition wire 12 are disposed in the lower space of the reconnection part 5.

[0030] The bus bar 3 has a thick portion 3a, a part of which is located outside the case body 2, a thin portion 3b, which is located in the center of the case body 2 in the left-right direction D2 and directly below the cutting tip 4c of the cutting portion 4, and a connecting portion 3c, which connects the thick portion 3a and the thin portion 3b.

[0031] The thin portion 3b is provided as a cutting portion that divides the bus bar 3 into a first portion 14 and a second portion 15 when the cutting portion 4 falls and hits against it (see FIG. 3).

[0032] The case body 2 is formed with a first restricting portion 16 that protrudes inward and restricts upward movement of the first portion 14 of the bus bar 3 in the first space 6. The case body 2 is also formed with a second restricting portion 17 that protrudes inward and restricts upward movement of the second portion 15 of the bus bar 3 in the first space 6.

[0033] The first restricting portion 16 and the second restricting portion 17 may be integrally formed as a circumferentially continuous flange that protrudes inward in the first space 6 .

[0034] 2. Various states of the fuse unit In addition to the normal state shown in FIG. 1 , the fuse unit 1 can assume two states in an emergency: a disconnected state in which a portion of the bus bar 3 is cut off and the electrical connection is severed, and a reconnected state in which the electrical connection that was interrupted in the bus bar 3 is restored.

[0035] An example of the disconnected state of the fuse unit 1 is shown in FIG.

[0036] When energy is applied to the explosive 9 via the ignition wire 8, the explosive 9 explodes. This causes a strong downward force to act instantaneously on the cutting portion 4, causing the large diameter portion 4a to climb over the support protrusion 2a and the cutting tip 4c to break through the thin portion 3b of the bus bar 3, thereby breaking the bus bar 3.

[0037] As shown in FIG. 5 , when the busbar 3 breaks, the tip of the first portion 14 and the tip of the second portion 15 may hang down and come into contact with the reconnection portion 5 .

[0038] Even in such a case, the insulating portion 11 is attached to the surface of the recess 5e of the reconnection portion 5, so that the first portion 14 and the second portion 15 are kept electrically disconnected.

[0039] Next, an example of the reconnected state of the fuse unit 1 is shown in FIG.

[0040] When energy is applied to the explosive 13 via the ignition wire 12, the explosive 13 explodes. This causes a strong upward force to act on the reconnection part 5, causing the flange part 5d to overcome the movement restricting part 2b, and pressing the first connection part 5b against the first part 14 and the second connection part 5c against the second part 15.

[0041] At this time, as shown in the respective figures, the first restricting portion 16 provided on the case body 2 restricts the upward movement of the first portion 14, thereby increasing the contact area between the first connecting portion 5b and the first portion 14. Similarly, the second restricting portion 17 provided on the case body 2 restricts the upward movement of the second portion 15, thereby increasing the contact area between the second connecting portion 5c and the second portion 15.

[0042] This suppresses an increase in contact resistance between the first connection portion 5b and the first portion 14, and an increase in contact resistance between the second connection portion 5c and the second portion 15, thereby ensuring good electrical conductivity between the first portion 14 and the second portion 15 of the busbar 3.

[0043] 6, the length of the reconnection portion 5 in the up-down direction D1 may be set so that the lower surface of the reconnection portion 5 is supported by the movement restricting portion 2b when the first connection portion 5b and the second connection portion 5c are pressed against the first portion 14 and the second portion 15, respectively. This makes it easy to maintain the state in which the first connection portion 5b and the second connection portion 5c are strongly pressed against the first portion 14 and the second portion 15, respectively.

[0044] 3. Modifications A first example of a modification is shown in Fig. 7. In this modification, a fuse unit 1A does not have an insulating portion 11 provided in the recess 5e of the reconnection portion 5.

[0045] In this modified example, the reconnection portion 5 is positioned below the bus bar 3 at a distance so that even if the tip ends of the broken first portion 14 and second portion 15 hang down as shown in FIG. 5 (shown by the two-dot chain line in FIG. 7 ), they will not reach the bus bar 3.

[0046] This prevents conduction between the first portion 14 and the second portion 15 via the reconnection portion 5 when the fuse unit 1A is in a disconnected state. Furthermore, not providing the insulating portion 11 reduces the number of components.

[0047] A second example of the modification is shown in Fig. 8. A fuse unit 1B in this modification differs from the above-described example in the shape of a case body 2B, a shape of a bus bar 3B, and a shape of a reconnection portion 5B.

[0048] First, the bus bar 3B has a thick portion 3a, a thin portion 3b, and a connecting portion 3c, but the portions disposed in the first space 6 and the second space 7 are substantially thin portions 3b.

[0049] The reconnection portion 5B, which is arranged in the second space 7 below the busbar 3B, comprises a cylindrical base 5f, a first connection portion 5b which protrudes upward from near one end of the base 5f in the left-right direction D2 and has a conical tip, and a second connection portion 5c which protrudes upward from near the other end of the base 5f in the left-right direction D2 and has a conical tip.

[0050] An upper portion of the base portion 5f is formed as a protruding engagement portion 5g that protrudes at least in the left-right direction D2. The protruding engagement portion 5g is positioned above the movement restriction portion 2b of the case body 2B, thereby restricting downward movement of the reconnection portion 5B (e.g., movement due to gravity). Unlike the other examples described above, no upward force is applied to the reconnection portion 5B by a spring member 10 or the like.

[0051] In addition, a second movement restriction portion 2c that restricts upward movement of the reconnection portion 5B is formed slightly above the portion on the inner surface of the second space 7 of the case body 2B where the protruding engagement portion 5g abuts.

[0052] That is, the reconnection portion 5B is held in a state in which the protruding engagement portion 5g is sandwiched between the movement restriction portion 2b and the second movement restriction portion 2c, so that movement in the up-down direction D1 is restricted.

[0053] The case body 2B does not include a first restricting portion 16 that restricts the upward movement of the first portion 14 of the bus bar 3B, and a second restricting portion 17 that restricts the upward movement of the second portion 15.

[0054] The reconnected state of fuse unit 1B in this modified example is shown in Fig. 9. As shown in the figure, when reconnection part 5B is moved upward with a strong force by exploding explosive 13 via ignition wire 12, first connection part 5b of reconnection part 5B penetrates first part 14 of broken bus bar 3B, and second connection part 5c penetrates second part 15.

[0055] The tip portions of the first portion 14 and the second portion 15 are conical in shape, making it easier for the first connecting portion 5b and the second connecting portion 5c to penetrate the first portion 14 and the second portion 15.

[0056] The first connecting portion 5b and the second connecting portion 5c may be provided with a barb so that the first portion 14 and the second portion 15 can be easily maintained in a penetrated state.

[0057] Furthermore, in order to allow the first connecting portion 5b and the second connecting portion 5c to easily penetrate the first portion 14 and the second portion 15, respectively, restricting portions may be provided to restrict the upward movement of the first portion 14 and the second portion 15. It is desirable that the restricting portions be provided so as not to interfere with the tip end of the first connecting portion 5b and the tip end of the second connecting portion 5c in the penetrated state.

[0058] Furthermore, to prevent the first connecting portion 5b and the second connecting portion 5c from interfering with the cutting portion 4 that falls from above, an escape hole may be formed in the cutting portion 4 to allow the tip of the first connecting portion 5b that has penetrated the first portion 14 to escape. Similarly, an escape hole may be provided in the cutting portion 4 to allow the tip of the second connecting portion 5c that has penetrated the second portion 15 to escape.

[0059] In addition, in order to prevent excessive downward movement of the cutting portion 4, specifically, to prevent downward movement of the cutting portion 4 to an extent that it interferes with the upward movement of the reconnection portion 5 after the bus bar 3 is cut, a regulating portion may be provided on the inner surface of the first space 6 of the case body 2B.

[0060] According to this modification, the first restricting portion 16 and the second restricting portion 17 of the case body 2B, the spring member 10, etc. are not provided, so that the weight of the fuse unit 1B is reduced.

[0061] A third example of the modification is shown in Fig. 10. In this modification, the shape of the cutting portion 4C of the fuse unit 1C is different from that of the above-described examples.

[0062] Specifically, the cutting portion 4C does not have a large diameter portion 4a or a small diameter portion 4b, but has a cylindrical portion 4d, a protruding portion 4e that protrudes outward at approximately the center of the cylindrical portion 4d in the vertical direction D1, and a cutting tip portion 4c.

[0063] Since the large diameter portion 4a, which has approximately the same diameter as the first space 6, is not provided, frictional resistance between the cutting portion 4 and the case body 2 is minimized after the protruding portion 4e climbs over the supporting protrusion 2a and is positioned below it during the transition from the normal state to the cutting state. Therefore, it is possible to break the bus bar 3 with the cutting tip 4c of the cutting portion 4 using less explosives 9.

[0064] A similar configuration can also be applied to the reconnection portion 5 .

[0065] In the above-described examples, the spring member 10 is used as a compression spring below the reconnection portion 5, but a spring member as a tension spring may be provided above the reconnection portion 5. In this case, the movement restricting portion 2b of the case body 2 only needs to be provided in a position and shape that restricts the upward movement of the reconnection portion 5.

[0066] 4. Summary As described in the above examples, the fuse unit 1 (1A, 1B, 1C) according to the present invention includes a bus bar 3 (3B) that is an electrical conductor and has a cut portion (thin portion 3b), a case body 2 (2B) that supports the cut portion at two points, a cutting portion 4 (4C) that is an insulator and is located in a first space 6 that is formed in the internal space of the case body 2 (2B) on one side of the bus bar 3 (3B), and a reconnecting portion 5 (5B) that is an electrical conductor and is located in a second space 7 that is formed in the internal space of the case body 2 (2B) on the opposite side of the bus bar 3 (3B) from the first space 6. The cutting portion 4 (4C) has a cutting tip 4c that cuts the bus bar 3 (3B) into a first portion 14 and a second portion 15 at the cut portion and is movable into the second space 7. The reconnecting portion 5 (5B) has a first connecting portion 5b that contacts the first portion 14 and a second connecting portion 5c that contacts the second portion 15. As a result, after the bus bar 3 (3B) is cut by the cutting portion 4 (4C) and the electrical connection between the first portion 14 and the second portion 15 is severed, the reconnecting portion 5 (5B) reestablishes the electrical connection between the first portion 14 and the second portion 15. For example, by applying the fuse unit 1 (1A, 1B, 1C) of the present invention to a vehicle, after the bus bar 3 (3B) is cut to avoid secondary damage due to a ground fault in the event of an accident, the electrical connection of the bus bar 3 (3B) can be restored, allowing the vehicle to be moved to ensure safety at the accident site. Furthermore, in extremely low temperatures, it is conceivable that occupants would stay inside the damaged vehicle and wait for rescue while keeping warm. However, by restoring the electrical connection of the bus bar 3 (3B), it becomes possible to use power from the vehicle battery to air-condition the interior of the vehicle, thereby improving the chances of occupant survival.

[0067] The reconnection portion 5 (5B) in the fuse unit 1 (1B, 1C) according to the present invention may have a U-shape in which the first connection portion 5b and the second connection portion 5c are protruding toward the bus bar 3 (3B), and an insulating portion 11 may be provided in the U-shaped recess 5e of the reconnection portion 5 (5B). As a result, even if both the tip ends of the first portion 14 and the second portion 15 of the broken bus bar 3 (3B) come into contact with the reconnection portion 5 (5B), the portion where the two tip ends contact is the insulating portion 11. This prevents unintended restoration of the electrical connection between the first portion 14 and the second portion 15, thereby improving safety. Furthermore, providing the insulating portion 11 in the recess 5e but not at the tip ends of the first connection portion 5b and the second connection portion 5c prevents the restoration of the electrical connection between the first portion 14 and the second portion 15 from being hindered.

[0068] The case body 2 in the fuse unit 1 (1A, 1C) according to the present invention may include a first restricting portion 16 that restricts movement of the first portion 14 toward the first space 6 and a second restricting portion 17 that restricts movement of the second portion 15 toward the first space 6. This restricts movement of the first portion 14 and the second portion 15 toward the first space 6 when the first connecting portion 5b and the second connecting portion 5c are pressed against the first portion 14 and the second portion 15, respectively, ensuring a good connection. This allows for favorable recovery of the electrical connection between the first portion 14 and the second portion 15. Furthermore, the contact area between the first portion 14 and the first connecting portion 5b and the contact area between the second portion 15 and the second connecting portion 5c can be increased, thereby suppressing an increase in contact resistance and reducing power consumption.

[0069] The fuse unit 1 (1A, 1C) according to the present invention may include a spring member 10 that biases the reconnection portion 5 in a direction toward the bus bar 3, and the case body 2 may include a movement restricting portion 2b that restricts movement of the reconnection portion 5 in a direction toward the bus bar 3. Thus, simply releasing the restriction imposed by the movement restricting portion 2b presses the first connection portion 5b and the second connection portion 5c of the reconnection portion 5 against the first portion 14 and the second portion 15, respectively, thereby restoring the electrical connection between the first portion 14 and the second portion 15. Therefore, a motor drive or the like is not required to bring the first connection portion 5b and the second connection portion 5c into contact with the first portion 14 and the second portion 15 during reconnection. Various configurations of the movement restricting portion 2b are conceivable. For example, the movement restricting portion 2b may be configured to be movable between a state in which it protrudes from the inner wall of the case body 2 and a state in which it is retracted. In this case, it is not necessary to place explosives 13 below the reconnection portion 5, thereby contributing to improved safety.

[0070] The spring member 10 in the fuse unit 1 (1A, 1C) according to the present invention may bias the reconnection portion 5 in a direction to bring it closer to the bus bar 3 (3B) with the first connection portion 5b in contact with the first portion 14 and the second connection portion 5c in contact with the second portion 15. This maintains the state in which the first connection portion 5b is pressed against the first portion 14 and the second connection portion 5c is pressed against the second portion 15 after reconnection. This therefore ensures a continuous electrical connection between the first portion 14 and the second portion 15 after reconnection.

[0071] The above-described embodiments and modifications can be combined as appropriate.

[0072] REFERENCE SIGNS LIST 1, 1A, 1B, 1C fuse unit 2, 2B case body 2b movement restricting portion 3, 3B bus bar 3b thin portion (portion to be cut) 4, 4C cut portion 4c cut tip portion 5, 5B reconnection portion 5b first connection portion 5c second connection portion 5e recess 6 first space 7 second space 10 spring member 11 insulating portion 14 first portion 15 second portion 16 first restricting portion 17 second restricting portion

Claims

1. A fuse unit comprising: a busbar having a conductor and a cut portion; a case body supporting two points on either side of the cut portion; a cutting portion made of an insulator and located in a first space formed in one side of the busbar within the internal space of the case body; and a reconnecting portion made of a conductor and located in a second space formed in the internal space of the case body on the opposite side of the busbar to the first space, wherein the cutting portion cuts the busbar into a first portion and a second portion at the cut portion and has a tip portion movable into the second space, and the reconnecting portion has a first connecting portion contacting the first portion and a second connecting portion contacting the second portion.

2. The fuse unit according to claim 1, wherein the reconnection portion is U-shaped with the first connection portion and the second connection portion protruding toward the bus bar, and an insulating portion is provided in the U-shaped recess in the reconnection portion.

3. A fuse unit as described in claim 1, wherein the case body is provided with a first restricting portion that restricts movement of the first portion toward the first space, and a second restricting portion that restricts movement of the second portion toward the first space.

4. A fuse unit as described in claim 1, further comprising a spring member that biases the reconnection portion in a direction approaching the bus bar, and the case body is provided with a movement restricting portion that restricts movement of the reconnection portion in the direction approaching the bus bar.

5. The fuse unit according to claim 4, wherein the spring member biases the reconnection portion in a direction approaching the bus bar when the first connection portion is in contact with the first portion and the second connection portion is in contact with the second portion.

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