Fuse with separating element

Abstract

The invention relates to a safety device (1), comprising: a fusible member (2) having a first segment (3), a second segment (4), and a connecting segment (5), which connects the first segment (3) to the second segment (4). The safety device (1) further comprises a separation element (6), configured to suppress a light arc between the first segment (3) and the second segment (4). The first segment (3) of the fusible member (2) extends along a first side of the separation element (6), the second segment (4) of the fusible member (2) extends along a second side of the separation element (6) located opposite the first side, and the connecting segment (5) of the fusible member (2) extends along a third side of the separation element. It is thus achieved that a light arc between the first segment (3) and the second segment (4) of the fusible member (2) cannot exist even if the spatial distance between the first and the second segment (3, 4) of the fusible member (2) is so minimal that it allows a skipping of a light arc.

Claims

1. A fuse (1) comprising: a U-shaped fusible element (2) with a first portion (3), a second portion (4) generally parallel to the first portion (3), and a connecting portion (5) which connects the first portion (3) to the second portion (4), such that the first portion (3), the second portion (4), and the connecting portion (5) define a plane, a separating element (6) which is configured to prevent an arc between the first portion (3) and the second portion (4), a first field-generating device (7a) for generating a first magnetic field in the region of the connecting portion (5), and a second field-generating device (7b) for generating a second magnetic field in the region of the connecting portion (5), wherein the first and second field-generating devices (7a, 7b) are permanent magnets, wherein the first portion (3) of the fusible element (2) extends on a first side of the separating element (6), wherein the second portion (4) of the fusible element (2) extends on a second side of the separating element (6), which is situated opposite the first side, wherein the connecting portion (5) of the fusible element (2) extends on a third side of the separating element (6), wherein the first and second field-generating devices (7a, 7b) are positioned on opposite sides of the fusible element (2) and on opposite sides of the plane, and wherein the first and second magnetic fields are directed in such a manner that an arc, caused by a current, between the first portion (3) and the second portion (4) is directed toward the separating element (6).

2. The fuse (1) as claimed in claim 1, characterized in that in each instance a part of the first portion (3) and of the second portion (4) of the fusible element (2) projects into a region beyond the separating element (6), and the first portion (3) of the fusible element (2) and the second portion (4) of the fusible element (2) are connected to one another in this region via the connecting portion (5).

3. The fuse (1) as claimed in claim 1, characterized in that the connecting portion (5) of the fusible element (2) is configured to melt temporally ahead of the first portion (3) and ahead of the second portion (4) in the event of a high current through the fusible element (2).

4. The fuse (1) as claimed in claim 1, characterized in that the separating element (6) comprises a ceramic.

5. The fuse (1) as claimed in claim 1, characterized in that the fuse (1) is configured for a voltage range up to 1 kV.

6. The fuse (1) as claimed in claim 1, characterized in that the fuse (1) is suitable for separating a current of up to 10 kA.

7. A vehicle battery with a fuse (1) as claimed in claim 1.

8. The fuse (1) as claimed in claim 1, characterized in that the fuse (1) is configured for a voltage range between 430 V and 470 V.

9. The fuse (1) as claimed in claim 1, characterized in that the fuse (1) is suitable for separating a current between 7 kA and 9 kA.

10. The fuse as claimed in claim 1, wherein the first and second field-generating devices (7a, 7b) are arranged in the region of the third side of the separating element (6), wherein the first and second field-generating devices (7a, 7b) extend parallel to the plane of the fusible element (2), and wherein the first and second field-generating devices (7a, 7b) extend from the first side of the separating element (6) to the second side of the separating element (6).

11. The fuse (1) as claimed in claim in claim 1, wherein the first and second field-generating devices (7a, 7b) extend parallel to the plane from the first side of the separating element (6) to the second side of the separating element (6), and wherein the first and second field-generating devices (7a, 7b) are each spaced from the fusible element (2) in a direction that is perpendicular to the plane.

12. The fuse as claimed in claim 11, wherein the first and second field-generating devices (7a, 7b) are arranged in the region of the third side of the separating element (6), wherein the first and second field-generating devices (7a, 7b) extend parallel to the plane of the fusible element (2), and wherein the first and second field-generating devices (7a, 7b) extend from the first side of the separating element (6) to the second side of the separating element (6).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) An embodiment of the invention will be described in detail with reference to the accompanying drawing. In the drawing:

(2) FIG. 1 is a schematic view of a cross section through a fuse according to the embodiment of the invention,

(3) FIG. 2 is a further schematic view of a cross section through a fuse according to the embodiment of the invention, and

(4) FIG. 3 is a schematic view of a cross section through a fuse according to the state of the art.

(5) FIG. 4 is a schematic view of a cross section through a fuse according to an embodiment of the invention.

(6) FIG. 4A is a schematic view of a cross section through a fuse according to an embodiment of the invention, illustrating a magnetic field and an arc that is directed toward a separating element.

(7) FIG. 5 is a schematic view of a cross section through a fuse according to an embodiment of the invention.

(8) FIG. 5A is a schematic view of a cross section through a fuse according to an embodiment of the invention, illustrating a magnetic field and an arc that is directed away from a separating element.

DETAILED DESCRIPTION

(9) FIG. 1 shows a schematic view of a cross section through a fuse 1 according to an embodiment of the invention. The fuse 1 includes a fusible element 2 with a first portion 3, with a second portion 4, and with a connecting portion 5. The material of the fusible element has been chosen in such a way that the latter is both electrically conductive and, in the event of high currents, is heated up in such a manner that its melting-point is exceeded. In the embodiment shown here, the fusible element 2 consists of copper.

(10) The fuse further includes a separating element 6 which has been configured to prevent an arc between the first portion 3 and the second portion 4. An arc may arise, in particular, in the case of a short circuit, and is able to bridge an air gap in the fusible element 2. The separating element 6 therefore consists of ceramic, in order to offer a high insulation resistance and a high thermal resistance.

(11) The connecting portion 5 and a part of the first and second portions 3 and 4 that is situated on the side of the connecting portion 5, and also a portion of the separating element 6, are surrounded by a fuse housing 8.

(12) The first portion 3 of the fusible element 2 extends on a first side of the separating element 6. The second portion 4 of the fusible element 2 extends on a second side of the separating element 6, which is situated opposite the first side. The separating element 6 has accordingly been arranged spatially between the first portion 3 and the second portion 4 of the fusible element 2. The separating member 6 in this embodiment has the shape of a plate. The plate has two opposing large-area sides and four peripheral sides with a smaller surface area. The first portion 3 and the second portion 4 of the fusible element 2 are respectively situated in the direction of the large-area sides of the separating element 6. In the direction of one of the sides with smaller surface area the first portion 3 and the second portion 4 project beyond the large-area sides of the plate or, to be more precise, of the separating element 6. Accordingly, in this region no separating element 6 is situated between the first and second portions 3 and 4. In this region the two portions 3 and 4 have been connected to one another by the connecting portion 5 of the fusible element 2. The connecting portion 5 of the fusible element 2 consequently extends on a third side of the separating element 6.

(13) The connecting portion 5 is smaller in its conductive cross section than the first and second portions 3 and 4 of the fusible element 2.

(14) By virtue of the fact that the separating element 6 has been constructed in the form of a plate, and the separating element 6 has a high electrical resistance, a path described by a least resistance between an arbitrary point of the first portion and an arbitrary point of the second portion is lengthened by the separating element. This does not apply to the regions of the first portion 3 and of the second portion 4 that project beyond the large-area sides of the plate or of the separating element 6.

(15) The first portion and the second portion of the fusible element 2 respectively project outward at their ends situated opposite the connecting portion 5 on one side of the fuse housing 8. These projecting ends of the fusible element 2 serve as terminal contacts of the fuse 1. At these contacts the fuse is integrated into an electric circuit to be protected. Also in this region, which is situated outside the fuse housing 8, the separating element 6 has been arranged between the large-area sides of the separating element 6. The separating element 6 projects further out of the fuse housing than the first and second portions 3 and 4 of the fusible element 2. As a result, a spark-over of the arc outside the fuse housing is also prevented.

(16) In the region of the connecting portion 5 two permanent magnets 7 have been arranged by way of field-generating devices for generating a magnetic field, as illustrated by FIGS. 4 and 5. The two permanent magnets 7 have been arranged on either side of the fusible element 2. Since in FIG. 1 which is shown it is a question of a cross section through the fuse 1, only one of the permanent magnets 7 is apparent. As illustrated in FIGS. 4 and 5, depending on the polarity of the permanent magnets 7, in the region between the permanent magnets 7 the arc is directed toward the separating element 6 or away from the separating element 6. Both orientations of the permanent magnets 7 are advantageous. If the arc is directed toward the separating element 6, it is interrupted by the latter. If the arc is directed away from the separating element 6, the distance to be bridged by the arc is lengthened, and in this way the arc is interrupted. In addition, the first portion 3 and the second portion 4 are repelled by the Lorentz force in the case of a short circuit, and the distance to be bridged by the arc is enlarged further by a displacement of the portions.

(17) FIG. 2 shows the fuse 1, which is also shown in FIG. 1, in a further cross section. In this case the arrangement of the first portion 3 and the second portion 4 of the fusible element 2 on the opposing sides of the separating element 6 is likewise apparent. It also becomes apparent here, and in FIGS. 4 and 5, that two permanent magnets 7 a and 7 b have been arranged on opposite sides of the fusible element 2.

(18) If a short circuit occurs in the electric circuit into which the fuse 1 has been integrated, a high current flows through the fusible element 2 via the terminal contacts. As a result, the fusible element 2 is heated up and begins to melt. Since the conductive cross section of the fusible element 2 is smallest at the connecting section 5, the fusible element is firstly separated by the melting process in this region. Since initially only a small air gap arises in the fusible element 2, the arc is able to flash over between the not yet molten parts of the separating element. By virtue of the magnetic field of the permanent magnets, this arc is directed toward the separating element 6. Since the latter consists of an insulating ceramic, the arc is severed. The electric circuit is consequently interrupted by the fuse 1.

(19) By virtue of the fact that in the event of a short circuit the arc no longer has to be extinguished by the lengthening of the clearance as a result of the fusible element 2 melting away, but rather the direct path of the arc is interrupted by the separating element 6, significantly fewer constrictions have to be built in. In this regard, the constrictions of a previously described fuse according to the state of the art can be compared with the connecting portion 5 of fuse 1. When the connecting portion 5 is melting away, the arc can no longer remain directly between the first portion 3 and the second portion 4 of the fusible element 2. The clearance between the two poles is significantly lengthened by the separating element.

(20) Depending on the orientation of the poles of the permanent magnets 7a and 7b, the current is directed outward (away from the separating element 6) or inward (toward the separating element 6) by the Lorentz force. If the current is directed outward, this lengthens the clearance to be bridged. The arc possibly does not touch the separating element 6. If the current is directed inward, the arc is separated by the separating element 6. To this end, the separating element must be designed to be sufficiently stable and heat-resistant.