Bent MIDI or safety fuse

A safety fuse includes a housing, a first contact blade having a protruding portion protruding from the housing along a first direction, a second contact blade having a protruding portion protruding from the housing, and a fusion section enclosed in the housing and connecting the first contact blade and the second contact blade. The protruding portion of the first contact blade includes two lateral edges extending in the first direction and a linear bend arranged on one of the lateral edges. The bend extends in a second direction perpendicular to the first direction.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a U.S. National Phase of PCT/EP2012/059493, filed May 22, 2012, which claims the benefit of priority to German Patent Application No. 20 2011 050 310.0, filed May 31, 2011, the contents of both of which are incorporated herein by reference.

TECHNOLOGY FIELD

The invention relates to a safety fuse for use in a motor vehicle. Such safety fuses are used to protect an electrical circuit from overloading. The invention furthermore relates to a bus bar and an arrangement with one or more such fuses.

BACKGROUND

So-called MIDI fuses are known in the prior art, as shown inFIG. 1, or described in German patent DE 10 2005 027 681 A1.

The fuse shown inFIG. 1has a first contact blade11, a second contact blade12and a fusion section (not shown), where the fusion section connects the first contact blade11with the second contact blade12. The first contact blade11, the second contact blade12, and the fusion section are arranged in a common plane. The fusion section is enclosed by a housing13, which is made of a nonconductive material, such as plastic. At least one portion of the first contact blade11, and at least one portion of the second contact blade12, protrude freely in opposite directions from housing13. The fuse10has an opening14in the portion of the first contact blade11that protrudes from housing13, allowing the fuse to be fastened to another part. Moreover, housing13protrudes relative to the common plane on either side of the plane and at about the same distance away from the plane.

If fastening fuse10, shown inFIG. 1, to another part, e.g., with a screw, the torque applied to establish the screw connection is initiated by friction in the first contact blade11, e.g., between the screw head and the first contact blade11, causing fuse10to rotate, or when fastening the second contact blade12to another part, the portion between the first contact blade11and the second contact blade12is subjected to torque. A large part of the torque is absorbed by housing13, whereby a part of the torque acts on the fusion section, i.e., mechanically loading the fusion section. This mechanical load affects the triggering properties of the melting temperature range.

SUMMARY

An object of the invention is to provide a fuse, in which a mechanical load of the melting temperature range is avoided.

This object is achieved by the fuse according to appended claims.

The invention is based on a fuse, especially for use in a motor vehicle, e.g., a MIDI fuse, as described at the beginning.

The invention provides that a preferably form-locking securing element, in particular an anti-rotation element, is arranged on an area or a portion protruding from a housing of a first contact blade of the fuse. The securing element preferably extends approximately vertically to the direction, in which the portion of the first contact blade protrudes from the housing, and/or approximately vertically or perpendicularly to a plane defined by the portion protruding from the housing of the first contact blade. The securing element is used to secure the fuse on a device, in particular a fastening element and/or a connecting element, e.g., a base or a cable lug, thereby diverting a lateral force acting on the fastening or connecting element and/or the fuse on the fastening or connecting element, due to the preferably rail- and/or flank-like securing element, in particular a guide rail, thereby preventing the application of a force on the fusion section and/or the housing. Specifically, the securing element prevents rotation of the fuse or the first contact blade, particularly in a plane defined by the portion of the first contact blade protruding from the housing, relative to the device, especially the base on which the first contact blade may be fastened.

The first contact blade and the fusion section, and optionally a second contact blade, may be arranged in a common plane or in planes arranged parallel to one another.

One embodiment according to the invention provides that at least one bend is arranged on at least one lateral edge of the portion of the first contact blade protruding from the housing. In the preferred embodiment with two lateral edges, the opposing lateral edges extend in the direction in which the portion of the first contact blade protrude from the housing. For example, the two lateral edges laterally define the first contact blade.

In an arrangement in which the fuse is mounted on a base, the base is enclosed between the bends of the first contact blade. The bends thus encompass the base at least partially, and preferably on its shoulders. These bends advantageously provides rotation prevention between the base and the first contact blade. This rotation prevention prevents rotation of the fuse of, in particular, the first contact blade, in the plane of the first contact blade relative to the base. The base may be made of plastic.

Preferably, the first contact blade is fastened to the base by a screw connection. If a torque is applied to establish the screw connection in the first contact blade, this torque is transmitted to the base via the bends encompassing the base in order not to subject the fusion section to the said torque.

Preferred embodiments of the invention are described below with reference to the figures. The features disclosed there, separately and in any combination, represent an advantageous further development of the object of the invention.

DESCRIPTION OF THE EMBODIMENTS

In the following figures, similar elements are each denoted by the same reference numerals.

FIG. 2shows a fuse10, which is a further development according to invention of fuse10ofFIG. 1.

Fuse10ofFIG. 2has a first contact blade11, a second contact blade12, and a fusion section16(schematically depicted using dashed lines) connecting the first contact blade11with the second contact blade12. The fusion section16can be a fusion section described, e.g., in the aforementioned German patent DE 10 2005 027 681 A1. Compared with the first and second contact blades11,12, the conduction cross-section of the fusion section16is smaller. If a current flowing between the first contact blade11and the second contact blade12exceeds the rated current, i.e., its amperage exceeds the amperage allowed for continuous operation of fuse10, the fusion section16overheats and melts or blows, thus interrupting the current flowing between the first contact blade11and the second contact blade12.

The first contact blade11, the second contact blade12, and the fusion section16are made of an electrically conductive material, e.g., metal. Preferred metals are copper or zinc, or copper- or zinc-based alloys. Contact tongues11,12, and the fusion section16are preferably punched from a plate-shaped semifinished product, e.g., a metal sheet, particularly a copper or zinc plate, or a tin-coated copper plate. Contact tongues11,12and the fusion section16are thus integral.

The first contact blade11and the fusion section16, and in this example, also the second contact blade12, are arranged in a common plane. In principle, it would be possible also to arrange the first contact blade11, the fusing section, and in particular the second contact blade12in parallel and spaced-apart planes.

Moreover, fuse10has a housing13that encloses fusion section16, from which at least a portion of the first contact blade11, and at least a portion of the second contact blade12protrude freely. The first contact blade11and the second contact blade12protrude in opposite directions from housing13. The portion protruding from housing13of the first contact blade11has an opening14with a closed, more specifically a circular cross-section. Opening14serves to fasten fuse10to a base31, as described below. The second contact blade12in the shown embodiment has no opening. Advantageously, the opening is punched during the punching of contact blades11,12and the fusion section16.

Whereas the lateral edges11a,11bin the fuse shown inFIG. 1and extending in the direction in which the portion protruding from the housing of the first contact blade11protrudes from housing13are not bent, bends15a,15bare arranged on the opposite lateral edges11a,11bof the first contact blade11of fuse10inFIG. 2. In the example shown, a single bend15a,15bis arranged and shaped as a straight or plane flank for each lateral edge11a,11b. Alternatively, on either lateral edge11a,11b, several bends15a,15bmay be arranged. The bends15a,15bor flanks may be arranged at approximately right angles relative to the common plane or the planes parallel to one another of the fusing section, and the first contact blade11or the plane of the first contact blade11. In the shown example, bends15a,15bextend along the whole length of the portion protruding from housing13of the first contact blade11.

As the bends15a,15bare formed on lateral edges11a,11b, they can be relatively easily produced during or after punching by reshaping, e.g., by bending. Thus, the first contact blade11, the second contact blade12, the fusing section, and the bends15a,15bmay be made by punching and bending the plate-shaped semifinished product.

The first contact blade11, may have, e.g., a portion enclosed by housing13(not shown). This is likewise the case for the second contact blade12. The lateral edges of the portion protruding from housing13of the first contact blade11may have bends15a,15b, whereas the lateral edges of the portion enclosed by housing13of the first contact blade11have no bends.

The fusion section16preferably joins the first contact blade11and the second contact blade12, in particular the portion enclosed by housing13of the first contact blade11and the portion enclosed by housing13of the second contact blade12. Housing13is fastened to the enclosed portion of the first contact blade11and/or encompasses snugly the first contact blade11, in the area where the portion of contact blade11is arranged in housing13. The same applies to the second contact blade12. Housing13forms a slit-shaped opening for the first contact blade11, as well as the second contact blade12.

Housing13protrudes relative to the common plane, in which the first contact blade11and the second contact blade, as well as the fusing section, are arranged, on either side of the plane at about the same distance away from the plane. This result in a compact design for fuse10.

As can be best seen inFIG. 3, several fuses10are attached to a common bus bar20in preferred further developments. Alternatively, fuse10may be formed integrally with bus bar20.

If changes are made in the fusion sections16, the punching tool for the fusion sections16formed integrally with bus bar20needs changing, whereas if fuses10are attached separately to bus bar20, changes can very easily be done by replacing the fuses10to be added to bus bar20resulting in tooling cost savings.

The second contact blade12is preferably placed against bus bar20, in particular flat against bus bar20. Bus bar20and contact blade12are preferably connected with a non-detachable joint21, i.e., separation of the second contact blade12from bus bar20is only possible by causing irreversible destruction of joint21. Alternatively, detachable joints, such as screw connections may be provided in order to connect the second contact blade12with bus bar20.

In the example shown, the second contact blade12is connected to bus bar20by a press joint21, which joint21is of the non-detachable kind. Press joints are known in the art as TOX® joints.

FIG. 3furthermore shows an arrangement with a base31, on which fuse10ofFIG. 2is mounted.

Base31is formed of a plastic material, and preferably integrally with a carrier30. Base31comprises a screw bolt32or a screw-like device with a threaded section, a supporting area and a clamping area. Screw bolt32may be clamped by pressing or inserting screw bolt32into the plastics material, or preferably by extrusion coating of screw bolt32with plastic during the manufacturing of base31. Besides supporting fuse10at the base31(i.e., inside), enclosure of fuse10may also take place from the outside. In this case, outer abutment surfaces are guided along the contour of fuse10. The tuning of the width of base31relative to the width of the fuse is optimized in terms of dimensional clearance.

Base31is enclosed between the bends15a,15bof the first contact blade11, in particular with no or only very slight clearance. Thus, the distance between bends15a,15bof the first contact blade11is approximately the width of base13arranged between these bends15a,15b. This prevents rotation of the first contact blade11relative to base31in the plane of the first contact blade11. A torque applied to the first contact blade11due to friction by the screw connection, with which the first contact blade11is fastened to base31, is transferred to based31via bends15a,15benclosing base31, such that the fusion section16is unaffected by the torque.

The portion of the first contact blade11protruding from housing13is enclosed, in particular clamped, between base31and a threaded means33, which in the shown embodiment is a nut. Base31of plastic has a threaded insert in the form of a screw bolt32. Screw bolt32is connected to an electrical conductor leading to one or more appliances. Screw bolt32extends through opening14of the first contact blade11, whereby nut33is screwed onto the screw bolt32.

Alternatively, the threaded insert inserted in base31may be a nut, into which the threaded means in the shape of a screw is fastened, whereby the first contact blade11is enclosed, in particular clamped, between the screw head and base31.

The bends15a,15bthus prevent rotation of the first contact blade11relative to base31about the screw axis of the threaded means and/or the threaded insert.

The shape of fuse10may be designed asymmetrically relative to its contact blades11,12, i.e., the first contact blade11provided with the opening is longer than the second contact blade12. Thus, a sufficient clearance, e.g., for mounting large lugs or other connection devices, is created between the fastened cable lug and the fuse housing13, which is preferably made of plastic.