Electrical connection for motor vehicle cable

A connection comprising, a connecting part, a sleeve materially bonded to the connecting part and having a through-opening extending in a longitudinal direction, and a bolt connected to the sleeve and having a bolt shank and a bolt flange, the bolt being crimped with its bolt shank in the longitudinal direction in the through-opening of the sleeve, the bolt is arranged with its bolt flange in a recess arranged at a front face of the sleeve, characterized in that the sleeve is connected to the connecting part by its front face located at the front face end.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the national phase entry of international patent application no. PCT/EP2022/055283, filed Mar. 2, 2022, and claims the benefit of German patent application No. 10 2021 105 747.7, filed Mar. 10, 2021, the disclosures of which are incorporated herein by reference in their entirety.

TECHNICAL FIELD

The subject matter relates to an electrical connection, in particular a connection between a connecting part and a flat part.

BACKGROUND ART

In electrical connection technology, especially in automotive applications, it is common practice to realize detachable connections between two electrical conductors by means of a bolt arranged on one of the conductors. A bolt is arranged on a flat surface of one of the conductors and is used for screwing to the other conductor. A bolt can be arranged on a conductor either as a through bolt through a hole in the conductor or as a welding bolt. A welding bolt is welded to a flat surface of a conductor, for example by means of friction welding, in particular rotary friction welding. The second conductor can then be placed on the welding bolt and screwed to the first conductor via a nut screwed to the bolt. The conductors are pressed against each other by the contact force of the nut and an electrically conductive path is formed between the conductors primarily via their immediate contact surface as well as via the bolt.

The conductor onto which the bolt is welded is usually a flat part, in particular a flat conductor or an electrical attachment part with a flat surface. In the field of power cables, copper conductors are usually used. Aluminum conductors are also possible. In order to avoid contact corrosion at the transition between the conductor and the bolt and thus ensure a long-lasting stable connection, the bolt is usually made of the same material as the conductor. For aluminum connections, the connection should be protected against environmental influences so that it is protected against contact corrosion. This is usually copper, so both bolt and conductor should be formed from copper or a copper alloy.

While copper has very good electrical and thermal conductivity, which is beneficial to the connection itself, copper is relatively ductile. This means that when the second conductor is bolted to the first conductor via the bolt, the tightening torque of the nut must not be too high. If a high tightening torque is required, there is always a risk that the thread of the bolt will shear off. Also with dynamic loads in continuous operation, such shear forces can occur on the thread that it shears off. This is particularly problematic when copper is used. On the other hand, the use of a bolt made of steel, in particular stainless steel, results in very good mechanical stability of a screw connection.

However, this increased mechanical stability compared with a bolt made of copper is “bought” by reduced electrical conductivity via the bolt. The bolt represents a relevant contact resistance at the junction of the conductors connected via the bolt.

The subject matter was thus based on the object of providing an electrical connection which meets increased mechanical requirements while maintaining the same electrical quality.

SUMMARY OF THE INVENTION

The connection comprises at least one connecting part. Such a connecting part can be formed as a strip or sheet. The connecting part is thereby in particular a flat conductor or a flat region of a round conductor. For example, a round conductor may be flattened at one end or in its course. The flattening can be introduced, for example, by forging, upsetting or the like.

It is also possible for the connecting part to be formed not from a solid material, in particular a single strand of a conductor, but also from a braid or fabric or a multi strand conductor. In this case, a flat area can be formed in the braid, fabric or strands by appropriate forming processes such as upsetting, pressing, welding or the like. A substantially inclusion-free area can be formed on a fabric tape by welding and/or compacting, for example, which can be processed like a solid material, in particular on which a sleeve can be applied.

For an electrical connection of the connecting part to a further connecting part, for example a conductor or the like, it is now proposed that an electrically conductive, in particular metallic sleeve is provided. The sleeve is connected to the connecting part by a material bond. The sleeve has a through-opening extending in its longitudinal direction. The sleeve is connected to the connecting part in particular in such a way that the longitudinal direction of the sleeve runs transversely to the longitudinal direction of the connecting part. In particular, the longitudinal direction of the sleeve runs parallel to the surface normal of the surface of the connecting part to which the sleeve is applied.

For a mechanical connection between the connecting part and the further connecting part, for example a conductor, a bolt is provided in addition to the sleeve. The bolt is connected to the sleeve. The bolt has a bolt shank. The bolt shank is also sleeve-shaped and has at least one blind hole, preferably a through-opening. This hole preferably extends into the bolt starting from the front face facing away from the bolt flange. Preferably, the hole extends as a through-hole between the distal front faces of the bolt. In the longitudinal extension of the bolt it has a flange pointing radially outwards and the bolt shank adjoining it. The bolt flange can also be understood as part of the bolt shank.

According to an alternative, the bolt has a bolt shank and a bolt head.

In the following, the bolt is described in two alternative embodiments. In the first embodiment, the bolt is sleeve-shaped with a through-opening and a bolt flange. Thus, the bolt shank is hollow.

In a second embodiment, the bolt has a bolt shank and a bolt head. The shank and/or the head are made of solid material without an opening.

The following explanations regarding the bolt may, as far as possible, apply to both alternatives. In particular, subsequent embodiments regarding the bolt head may, as far as possible, apply to the bolt flange. In particular, the fastening of the bolt in the sleeve may be the same for both alternatives.

While the sleeve is materially bonded to the connecting part, the bolt may be positively, non-positively and/or materially bonded to the sleeve. In particular, the outer lateral surface of the bolt shaft is in direct contact with the inner lateral surface of the through-opening. In this case, it is possible that a force fit or form fit is formed when the bolt is pushed into the through-opening. In particular, the bolt can also be driven into the through-opening in such a way that the cross-section of the through-opening changes from its original state as a result of the driving-in of the bolt. The bolt thereby plastically deforms the inner lateral surface of the through-opening. This is particularly possible if the bolt is made of a mechanically stronger material than the sleeve.

The sleeve has a recess at its one front face, which is formed to receive the bolt flange/head. When the bolt is inserted into the sleeve, i.e. with its bolt shank inserted in the through-opening, the bolt flange/head lies in the recess at the front face end. The recess has an extension in the longitudinal direction into the sleeve which is preferably greater than the extension of the bolt flange/head in the longitudinal direction of the bolt. Thus, the bolt flange/head is completely received in the recess.

The sleeve is then connected to the connecting part by its front face located at the front face end. The recess accommodates the bolt completely in the sleeve and the front face located at the front face end can be flat. The plane formed by this front face serves as the connection plane for the material connection with the connecting part.

The bolt thus received in the sleeve serves to absorb a tightening force when the second connecting part is clamped between the front face of the sleeve opposite the recess and a screw screwed to the bolt or a nut screwed to the bolt. An electrical path between the then screwed connecting parts occurs primarily from the subject connecting part via the sleeve to the second connecting part clamped to the sleeve. The second connecting part can be formed in accordance with the above explanations for the first connecting part, whereby a through-opening is provided in the flattening or in the flat area, into which the bolt can be inserted with its bolt shaft.

The bolt together with the sleeve thus forms a fastening means for a second connecting part to the first connecting part.

According to an embodiment, it is proposed that the bolt with its collar-shaped, radially outwardly projecting bolt flange/bolt head is mounted at least partially circumferentially on a circumferential shoulder in the recess of the sleeve. The shoulder is formed in the manner of a rebate in the recess of the sleeve. The bolt flange/bolt head projects radially outwardly with respect to the longitudinal direction of the bolt, in particular circumferentially. The cross-section of the bolt flange/bolt head is preferably round, but can also be polygonal, in particular hexagonal or octagonal. The cross-section of the recess can be adapted to the cross-section of the bolt flange/bolt head. Particularly in the case of a polygonal bolt flange/bolt head, this can secure the bolt in the sleeve against a torque directed around the longitudinal axis. This can simplify screwing a connecting part to the sleeve via the bolt.

The recess arranged at the front end of the sleeve preferably completely encloses the through-opening. Thus, the bolt flange/bolt head can be fully inserted into the recess and the bolt flange/bolt head no longer protrudes beyond the front end of the sleeve.

According to an embodiment, it is proposed that the hole is a blind hole or a through-hole. The hole of the bolt shaft preferably has an internal thread. The outer lateral surface of the bolt shaft is pressed into the sleeve. A screw can be screwed into the bolt shaft via the internal thread. This screw can be used to press a second connecting part onto the sleeve and thus onto the first connecting part.

According to an embodiment, it is proposed that the bolt shank protrudes from the through-opening with its shank end at an end of the sleeve distal to the recess. This protruding end is used to attach a second connecting part to the sleeve and consequently the first connecting part.

The bolt shaft may have a uniform cross-section along its longitudinal axis, or it may have different cross-sections. It is thus possible for the bolt shank to have regions with different radial projections in the region in which it is inserted into the through-opening. The through-opening can correspond to this and in particular have a corresponding opening cross section. Thus the bolt shank can be positively received in the region of the through-opening.

According to an embodiment, it is proposed that the bolt has an internal thread in its hole. With this internal thread, the bolt can be screwed with a screw. A second connecting part can be pressed against the sleeve and the bolt with the screw flange of a bolt screwed in this way. In this case, the bolt has a longitudinal extension such that in the inserted state, i.e. when the bolt shank is in contact with the sleeve within the recess, it does not project beyond the through-opening of the sleeve. In particular, the front faces of the sleeve and the bolt shank lie plane-parallel to each other on the side facing away from the recess.

According to an embodiment, it is proposed that one shank end of the bolt has a thread, in particular that the thread projects into the through-opening. Via this thread, the bolt can be screwed to a second connecting part. In particular, by means of a nut, the second connecting part can be pressed against the front face of the sleeve.

As already mentioned, the bolt shank can be positively received in the through-opening. For this purpose, according to an embodiment, the bolt is knurled at least in sections on its outer lateral surface, in particular in an area adjacent to the bolt flange. The knurled part has protrusions and recesses running in the longitudinal direction of the bolt shaft. The knurled part of the bolt shank is preferably pressed into the through-opening by means of an interference fit. This may involve plastic deformation of the inner lateral surface of the through-opening.

As already explained, it is preferred if the bolt is mounted in the sleeve so that it cannot rotate. This can be achieved in particular by pressing the bolt shaft into the through-opening.

According to an embodiment, it is proposed that the bolt flange/bolt head is arranged in the recess at a distance from the front face in the longitudinal direction. This achieves that, on the one hand, the front face can be welded flat to the connecting part and, on the other hand, the bolt flange is not in direct contact with the connecting part in the welded state.

In particular, the sleeve is formed from a copper material and the bolt from steel material. Preferably, the sleeve is made of a material that is more ductile than the material of the bolt. The combination of copper and steel has proved advantageous in this respect. Because the bolt is less ductile than the sleeve, it also offers greater resistance at its thread to shearing of the thread during screwing than if the bolt were formed from the material of the sleeve. The bolt can thus be screwed with a higher tightening torque, in particular a nut screwed onto the thread of the bolt or a screw screwed to the internal thread can be tightened with a higher tightening torque than if the bolt were formed from the material of the sleeve.

According to an embodiment, it is proposed that the sleeve with the front face located at the front face end is friction welded, in particular completely friction welded, to the connecting part. In particular, rotary friction welding can be used here. The sleeve can preferably have an area with different radial expansions. In particular, the outer cross section can be polygonal, so that a friction welding tool with a high torque enables friction welding. In this case, the sleeve does not have to be held in the friction welding tool by means of radially inwardly directed contact forces, but rather the energy can be applied to the outer lateral surface of the sleeve via the form fit between the sleeve and the friction welding tool.

According to an embodiment, it is proposed that a connection part with an opening is placed over the bolt shaft. The connection part has also been described previously as a second connecting part. The connection part may be formed according to the above description of the first connecting part. In particular, the connection part has a flat area or flattening with the opening.

In an alternative, the connection part can be arranged with its opening over the hole of the bolt shaft, in particular in alignment. A screw can then be inserted through the opening of the connecting part and screwed to the internal thread. The head of the screw is thus pressed against the connection part on the surface facing away from the sleeve. The bolt flange clamps the connecting part against the sleeve.

With a nut mounted on the bolt shank, the connection part can be clamped to the sleeve in an alternative. In this case, the nut can be screwed to the bolt shank with a tightening torque. The connection part is clamped to the sleeve via the nut. The connecting part is in direct contact with the end of the sleeve distal to the recess.

An electrical path between the connection part and the connecting part is provided in both alternatives primarily directly via the sleeve.

According to an embodiment, it is proposed that the connecting part, the sleeve and the bolt and the connection part are encapsulated in a common housing, wherein the connecting part and the connection part are led out of the housing in a moisture-tight manner.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

FIG.1ashows a first connecting part according to an embodiment. The connecting part2in the example shown is a flat conductor. The connecting part in all variants presented here can be formed from a copper material or an aluminum material.

The connecting part2has a longitudinal axis4, a vertical axis6and a transverse axis8. The connecting part2can have one or more flat connecting surfaces, which runs in particular parallel to a plane spanned by two of the axes4-8.

The connecting part2according toFIG.1bmay be shaped as a round conductor. A connecting area10may be provided at a front end or in the course of the conductor. The connectign area10may be formed as a flattening. In particular, the connecting area10is formed from the round conductor by upsetting or pressing.

FIG.1cshows a connecting part2as a stranded conductor, in which case a connecting area10is also formed at the front face. The stranded conductors can be compacted in the connecting area10and in particular welded or soldered together.

FIG.1dshows a connecting part2as a braided strip. The connecting area10can be formed in the course of the braided band or at a front face end. The strands of the braid can be joined to one another in the connecting area10, in particular joined to one another with a material bond, for example by means of ultrasonic welding or resistance welding. The embodiments described for the embodiments according toFIGS.1a-dcan be combined as desired for different connection parts2.

A sleeve is now proposed for connecting a connecting part2to a connection part.

FIG.2ashows a sleeve12. The sleeve12has a longitudinal axis14. The sleeve12has a through-opening16. The through-opening16extends from a first front face end18ato a second front face end18b. The longitudinal axis14extends between the two front face ends18a, b. In the region of a front face end18a, the sleeve12has a recess20. The recess20is preferably circumferentially bordered by the outer lateral surface of the sleeve12. In the region of the recess20, in particular centrally in the recess20, the through-opening16is provided.

FIG.2bshows the sleeve12in a longitudinal section. The recess20can be seen. It can also be seen that the sleeve12surrounds the recess20circumferentially. The through-opening16extends from the recess20toward the front end18b.

Sleeve12is preferably made of a copper material or aluminum material. In particular, sleeve12is made of the same material as the connecting part2. Materials can in particular be alloys, such as brass as a copper alloy.

The outer lateral surface as well as the cross-section of the recess20as well as of the through-opening16can be round or angular, in particular circular, elliptical or polygonal in shape.

FIGS.3a-cshow various embodiments of the sleeve in a plan view. InFIG.3a, the outer lateral surface of the sleeve12is octagonal. The recess20is adapted in cross-section thereto and is also octagonal. Inside the recess20, the through-opening16is arranged with a round cross-section.

FIG.3bshows a further embodiment in which the outer lateral surface of the sleeve12as well as the recess20are round, in particular circular. The through-opening16within the recess20, on the other hand, is hexagonal in shape.

FIG.3cshows, in contrast toFIG.3b, the through-opening16with a star-shaped cross-section. A wide variety of shapes can be combined with one another.

The cross-section of the bolt head26, as shown inFIGS.5aandb, may be adapted to a cross-section of the recess20. For example,FIG.5ashows a bolt head26with an octagonal cross-section, whereasFIG.5bshows a bolt head26with a star-shaped cross-section. These and other cross sections are conceivable. The cross sections of bolt head26and recess20can be congruent with each other, so that bolt head26can be positively received in recess20. This positive fit results in an anti-rotation lock of the bolt22in the through-opening16, so that the bolt22can be screwed to the sleeve12via the thread in the area28b.

In addition to various cross-sections of the bolt head as shown inFIGS.5a, b, the bolt shank28may also have a cross-section that is not circular, particularly in the region28a. For example,FIG.6ashows a bolt shank28in region28athat is oval.FIG.6bshows a bolt shaft28in a cross-section in region28athat is triangular, andFIG.6cshows a corresponding quadrangular cross-section.

The through-opening16as well as the cross section of the bolt shaft22in the area28amay be congruent to each other. Also, it is possible for the knurling in area28ato be such that its maximum diameter is slightly larger than the diameter of the through-opening16so that when the bolt22is pushed into the through-opening16, an interference fit is formed between the bolt26in area28aand the through-opening16. In this case, the knurling can lead to plastic deformation of the inner lateral surface of the through-opening16.

FIGS.7a-cillustrate the production of a connection according to the subject matter. First (FIG.7a), the bolt22is inserted into the sleeve12so that the bolt head26is recessed in the recess20. The bolt shank28has its region28awithin the through-opening16, whereas the bolt shank28has its region28bprotruding from the front end18bof the sleeve12.

After the bolt22has been inserted into the through-opening16, the sleeve12is joined to the connecting part2in the region of the front face end18a, in particular welded (FIG.7b). Here, a welding tool can press the sleeve12against the connecting area10by means of friction welding and cause the joining partners to melt by the rotational energy introduced. Resistance welding can also be performed.

After the sleeve12has been welded onto the connecting part2, a connection part30, which may be shaped in accordance with a connecting part described herein or in a shape deviating therefrom, can be fastened to the bolt22, in particular screwed. The connection part30is in particular a cable, in particular as described inFIGS.1a-d.

The connection part30has a through-opening32. With the through-opening32, the connection part30is fitted onto the bolt22, in particular the bolt shaft28in the region28b. A nut34is then screwed onto the bolt22. During screwing, the nut34presses the connection part30against the front face end18bof the sleeve12.

The bolt22is preferably formed from a harder material than the sleeve12, which means that the nut34can be screwed on with a higher tightening torque than if the bolt22were formed from the material of the sleeve12. In particular, the sleeve12is made of a copper material or aluminum material and the bolt22is made of a steel material.

The bolt flange46may be adapted in its cross-section, as shown inFIGS.9aandb, to a cross-section of the recess20. For example,FIG.9ashows a bolt flange46with an octagonal cross-section, whereasFIG.9bshows a bolt flange46with a star-shaped cross-section. These and other cross sections are conceivable. The cross sections of bolt flange46and recess20can be congruent with each other, so that bolt flange46can be positively received in recess20. This positive fit results in an anti-rotation fit of the bolt42in the through-opening16, so that the bolt42can be screwed to the sleeve12via the internal thread.

In addition to various cross-sections of the bolt flange according toFIGS.9a, b, the bolt shank48, in particular in the region of the knurling48a, may also have a cross-section that is not circular. Thus,FIG.10ashows a bolt shank48that is oval.FIG.10bshows a bolt shank48in a cross-section that is triangular, andFIG.10cshows a corresponding quadrangular cross-section.

The through-opening16as well as the cross section of the bolt shaft48may be congruent to each other. Also, it is possible for the knurling48ato be such that its maximum diameter is slightly larger than the diameter of the through-opening16so that when the bolt42is pushed into the through-opening16, an interference fit is formed between the bolt46and the through-opening16. Here, the knurling48amay result in plastic deformation of the inner lateral surface of the through-opening16.

FIGS.11a-cillustrate the production of an objective connection. First (FIG.11a), the bolt42is inserted into the sleeve12so that the bolt flange46is recessed in the recess20. The bolt shank48lies within the through-opening16, and the bolt shank48has a length equal to the length of the through-opening. As a result, the bolt shank48lies with its front face flush with the outer front face18bof the sleeve12. Also, the bolt shank48may be shorter so that it recedes behind the front face18bof the sleeve12.

After the bolt42has been inserted into the through-opening16, the sleeve12is joined, in particular welded, to the connecting part2in the region of the front face18a(FIG.11b). Here, a welding tool can press the sleeve12against the connecting area10by means of friction welding and cause the joining partners to melt by the rotational energy introduced. Resistance welding can also be performed.

After the sleeve12has been welded onto the connecting part2, a connection part30, which may be shaped in accordance with a connecting part described herein or in a shape deviating therefrom, can be fastened to the bolt42, in particular screwed. The connection part30is in particular a cable, in particular as described inFIGS.1a-d.

The connection part30has a through-opening32, and with the through-opening32, the connection part30is aligned with the bolt42and the sleeve12such that the through-opening32is aligned with the hole48b. A screw50is then screwed into the hole48bof the bolt42with the internal thread. As the bolt50is screwed into place, it presses the connecting member30against the front end18bof the sleeve12.

The bolt42is preferably formed of a harder material than the sleeve12, which results in the screw50being able to be screwed with a higher tightening torque than if the bolt42were formed of the material of the sleeve12. In particular, the sleeve12is formed of a copper material or aluminum material and the bolt42is formed of a steel material.

An electrical connection between the connection part30and the connecting part2is made in particular via the sleeve12. The bolt22preferably serves to mechanically fix the connection part30to the sleeve12, which in turn is joined to the connecting part2in the region of the front face end18aby a material bond.

LIST OF REFERENCE SIGNS