EP0859375B1 - Ignition line for motor vehicle and ignition line manufacturing method - Google Patents

Description

The invention relates to an ignition line for Motor vehicles according to the preamble of claim 1.

Ignition leads for automobiles are general due to the limited space in the engine compartment of the Motor vehicle as well as the mostly immediate proximity of the warm or hot parts of the engine block are subject to special loads exposed. Due to this, ignition leads are regarding the mechanical and thermal resilience To make demands. Because of the very high Voltages required to generate an ignition spark are the dielectric strength of ignition cables of highest importance. Ignition leads are therefore total To be carried out so that a high dielectric strength over the entire service life even with heavy use the ignition cable remains guaranteed.

As is known, the line capacity is also one Ignition cable a significant size, which is the ignition behavior of an ignition harness. A high line capacity causes the original firing pulses to be distorted, causing a higher number of misfires is caused. It is therefore the lowest possible capacity for an ignition cable to strive for. The capacity of an ignition wire is influenced by the choice of insulation material. there offers a material with the lowest possible dielectric constant the smallest possible capacity.

To achieve a low capacity, the electrical Surround the ignition cable with an insulating layer, which consists of a non-polar plastic as possible. Around thermal destruction of the insulating layer at high ambient temperatures counteracting this in the engine compartment usually surrounded by a coat, which consists of a thermal more stable material. This is an organosilicon Polymer used, which in addition to thermal stability also has advantageous mechanical properties.

A line with the above structure is in the EP 0 646 936 A1 discloses, but does not relate to an ignition line for motor vehicles. There a conductor is described, which an inner insulating layer and an outer insulating layer has, wherein the inner insulating layer is a polyolefin polymer and the outer insulating layer is an organosilicon Contains polymer. In particular, an insulating layer is disclosed which is a polyolefin copolymer and various additives, for example, metal hydrates. In particular the admixture of the additives becomes flame retardant or less harmful combustion gases and functional integrity aimed at in case of fire. The special material properties however, the inner insulation layer disclosed there leads to a comparatively high line capacity of those described there Management. It is also comparatively large technical effort connected.

The well-known polyolefins and silicone organic polymers have incompatible structures, so that these in generally do not merge. To solve the Connection problems of both insulation layers is in the above Scripture suggested, the inner and the outer To interlock the insulating layer in their border area. This interlocking is intended to provide a particularly reliable, mechanically firm connection of the two insulating layers achieved become. However, this represents a purely form-fitting Connection, which is already comparatively easy Coercive forces, like this for bends with a small radius of curvature can occur, can be destroyed. Even when separating a piece of pipe will cause the coat of the different deformation behavior of the jacket and Detach the cover at least locally from the inner insulating layer.

Because of this comparatively weak, exclusively mechanical Connection of insulating layer and jacket is also the axial displacement of the inner insulating layer with the Conductor with respect to the sheath not reliably prevented. In the case of permanent mechanical stress or if it already exists Detached sections of the sheath will become the insulating layer with the electrical conductor inevitably axially inside shift or turn the jacket. This creates Cavities lead to electrical in no time Destruction of the cable by leakage currents and glow. This shortens the life of such a cable.

A procedure continues to be used in the abovementioned document described for the manufacture of a line in which the inner insulating layer co-extruded with the outer insulating layer becomes. Due to the very different thermal properties the materials of the two layers is in the Coextrusion requires thermal separation. Otherwise the high temperature, which for the extrusion of the outer insulating layer or the Jacket are necessary, thermally damaged. Such a Thermal separation complicates the extrusion of a line.

DE 196 42 668 C1 is an ignition cable for motor vehicles known whose electrical conductor from one Polyethylene existing insulation layer is surrounded. The insulation layer is in turn surrounded by a coat made of There is silicone rubber. Between the insulating layer and the Coat is a skin layer that connects the two present, which the adhesion between the insulating layer and the coat. The material of the skin layer becomes common networked with the material of the jacket in order to increase To cause adhesive strength between the two. The DE 196 42 668 C1 is not prepublished.

It is therefore an object of the present invention to Ignition cable for motor vehicles with the aforementioned Form features so that they are thermally stable at the same time as well as mechanically resilient and as low as possible Has line capacity. Such an ignition line should The requirements of the thermal class D standard and the deformation forces are sufficient without destroying the connection of the insulating layer and coat resist.

This problem is solved by the features of the first Claim.

It is important for the invention that the jacket thermally stable material with the insulating layer made of polyethylene, which is a particularly low dielectric constant has, is connected by gluing. With an effective bond becomes a mechanical stability of the invention Ignition wire causes. The connection between jacket and insulation layer remains even with deformation stresses like this can occur in the engine compartment. In particular the separation of the jacket from the insulating layer is prevented. This will in particular transfer the tensile forces the insulation layer of the ignition cable is restricted. Work such Tractive forces to a large extent on the insulating layer, so it could spread to peeling zones as well deterioration of the isolation up to impairment of electrical contact. This would Leakage currents and sparks occur outside the combustion chamber, so that the number of misfires would increase. By Transfer of the sheath deformation (sheath crimp) Axial forces when there is tensile load on the insulating sleeve and conductor also increases the pull-out force of a cable connector, resulting in an improvement in operational safety of the cable set.

Through a firm connection between the jacket and the insulating layer is also caused, for example, by tensile forces partial exposure of the inner insulation layer effective prevented. This is of particular importance since it is already a small exposed section of the insulation due to the high Temperature in the engine compartment would be thermally damaged.

The polyethylene of the inner insulation layer is through effective gluing with the coat particularly effective against thermal damage protected. The polyethylene also shows a particularly low dielectric constant. A such an ignition line therefore has a particularly low overall Capacity. This requires a further reduction in the number of misfires.

Overall, the present invention presents itself with advantageous in particular electrical properties. In particular the low susceptibility to misfire is in With regard to future emission standards of the EC (Euro 2000) advantageous. This standard will register all misfires prescribe in the engine electronics (on-board-diagnostic 2).

Due to the above characteristics, the entire The load capacity of the ignition harness is increased.

Particularly effective bonding is achieved that an adhesive is at least partially in the insulating layer migrated and anchored in it. It is beneficial if an adhesive at least partially covers the surface of the Polyethylene insulating sleeve dissolves into the polyethylene structure penetrates and networked there. The adhesive is in the polyethylene insulating sleeve anchored. This creates a special one durable and strong adhesive bond, in which the Bonding zone is widened. Such a widened bond zone is especially in terms of incompatibility the polymer structures of polyethylene and silicone. It is preferably a continuous one Transition from insulating layer material to adhesives achieved, what the direct contact between polyethylene and silicone prevented.

An insulating layer pretreated in this way can moreover stored and later covered with the silicone jacket become. The adhesive in particular then no longer has to be introduced between the jacket and the insulating layer. Such an insulating layer also has none not hardened or damp glue, so that the insulating layer with the electrical conductor inside is easy to use. The crosslinking of the adhesive can for example by heat treatment of the insulating layer after applying the adhesive.

A particularly intensive and durable adhesive bond To achieve the jacket with the insulating layer, the invention designed so that the jacket with the adhesive is at least partially networked. The networking of the coat with the adhesive is preferably by the action achieved higher temperatures. It also makes sense if the Coat with the adhesive, which is on the insulating layer applied, connected to, or immigrated to this is partially networked. Networking can, for example by exposure to water vapor, high temperature and high pressure can be brought about.

A continuous change in concentration in radial Direction from polyethylene to silicone is achieved in that the bond zone between the insulating layer and the jacket in a radial Direction with an outer zone of the insulating layer and overlapped with an inner zone of the jacket. This will the direct contact between polyethylene and silicone prevents.

A particularly preferred embodiment of the present The invention is when the adhesive has a silane base. Silanes are suitable, silicone and polyethylene are effective to glue. Others can use the silane-based adhesive Fabrics, for example to adjust the consistency of the adhesive.

The silane-based adhesive also has the property of to network the silicone.

Leakage currents and breakdowns and related Misfires are also effectively contained by the fact that the Sheath of the ignition cable at the end with a grommet from a connector is glued. A gluing of the jacket and connector sleeve is tear-proof. It is an advantage if the spout consists essentially of organosilicon polymer consists. This allows a particularly firm connection by means of a silicone adhesive. A grommet made of silicone organic Polymer is also particularly heat-resistant.

The invention also relates to a method for Manufacture of an ignition cable for motor vehicles, the Insulating layer and the jacket are extruded.

The method is intended for the production of an inventive Ignition cable with permanent and particularly stable gluing be suitable for the jacket and insulating sleeve.

It is proposed that an adhesive on the Insulating layer is applied that the adhesive in the Insulating layer anchored and that the coat then on the insulating layer is extruded. The adhesive must be in the proposed method only on the insulating sleeve be applied. Through subsequent networking in one The furnace becomes the core consisting of an insulating layer and electrical Ladder exists, largely dried and it becomes a Connection of insulation layer and adhesive achieved. Thereby the wire is easy to handle and store, so that it can be used for subsequent extrusion of the jacket, for example Drums rolled up, can be kept ready.

The connection continues through the networking of the adhesive of the adhesive with the radially outer zone of the insulating layer causes. This has the ones already described above Benefits.

The subsequent extrusion of the jacket onto the insulating layer is in terms of thermal damage Insulating layer comparatively uncritical, because the insulating layer can be cold when extruding the jacket. The Sheath can be made by following the extrusion of the silicone crosslinking at high temperatures directly with crosslink the adhesive of the insulating layer. But it can a separate networking procedure can also be used, for example steam crosslinking.

This method is preferably carried out in such a way that a silane-based adhesive is used. Such a Glue can be applied to and with the insulating layer get connected. The insulation layer cross-linked with the adhesive then at higher temperatures with the jacket made of silicone organic Polymer.

It is particularly advantageous if the adhesive in an immersion process is applied. This procedure is simply by immersing the wire in a tank, which the Includes adhesive to realize. The amount of the applied adhesive e.g. by the viscosity of the adhesive and set by the speed of the wire become. The amount of adhesive applied is all the more larger, the higher the conveying speed of the wire.

The process is preferably carried out in such a way that an adhesive on the insulating layer by heat treatment is networked. This can be done for example by means of an elongated Oven, which the wire passes through.

The method is carried out in a particularly preferred manner, by applying the adhesive and crosslinking continuously in one coherent operation respectively. In addition to the process engineering simplification the advantage that the adhesive is homogeneous over the entire length of the cable is distributed and that networking done evenly. It is advantageous if in the same Additional drying takes place. By the drying process makes the wire rollable and therefore storable.

Finally, the method can advantageously be carried out in such a way that the extrusion of the jacket in another Operation takes place after the insulation layer has been crosslinked. The coating for the insulating layer in the immersion process Sintering is the required conveying speed of the wire comparatively low. Around the coat on the insulating layer being able to extrude is a higher conveying speed required. To drive at this increased speed can, it is necessary that the extrusion after the Sintering takes place in a separate operation.

Fig. 1

eine perspektivische Ansicht einer quergeschnittenen erfindungsgemäßen Zündleitung,

Fig.2

einen Querschnitt durch einen mit einer Zündleitung verbundenen Stecker, und

Fig.3

eine Verfahrensskizze eines erfindungsgemäßen Verfahrens.

The invention is explained with reference to exemplary embodiments shown in the drawing and a process sketch. It shows:

Fig. 1

2 shows a perspective view of a cross-sectional ignition lead according to the invention,

Fig. 2

a cross section through a plug connected to an ignition line, and

Fig. 3

a process sketch of a method according to the invention.

The same reference symbols always denote in all figures the same, constructive features.

1 shows a perspective view of an inventive Ignition cable 1, which is cut open transversely. The ignition line has a cylindrical cross section. The electrical conductor 2, which is made of there is a copper strand with individual wires 3. The electric one Conductor 2 is completely covered by an insulating layer 4. The insulating layer 4 is further out with a jacket 5 surrounded by silicone. The insulating layer 4 and the jacket 5 have an overlap with a in the radial direction 7 Bonding zone 6.

The bonding zone 6 has an annular cross section, it preferably has a continuous concentration curve in the radial direction 7 of pure polyethylene about a maximum concentration of the adhesive up to towards pure silicone.

The widths of the overlap areas determine, among other things the strength and durability of the adhesive connection. You can by varying the process parameters, such as Variation of the temperature of the furnace, the length of stay in the furnace or the extrusion speed or temperature can be set.

2 shows one on the end side 24 of an ignition line 1 glued plug 11. The plug 11 has a plug contact 12 on which with the electrical conductor of the ignition line is electrically connected. The connector sleeve 13 surrounds the plug contact 12 completely so that it is effective is electrically insulated. The spout is in an adhesive area 14 glued to the jacket 5 of the ignition line 1. The Spout 13 is pushed over the jacket 5, so that a Folded overlap results, which extends in the axial direction 8. The bonding area 14 extends over the entire foldover, so that the adhesive connection particularly is firm and there are no detached zones, which Could form crack nuclei. Creeping sparks from the plug neck are avoided.

The gluing serves in particular to maintain the insulation even under heavy mechanical stress, such as pulling out the plug 11 by pulling on the Ignition cable 1.

3 shows an overview sketch of an inventive Method for producing an ignition line according to the invention 1 for motor vehicles. The core, that is the insulating layer with electrical conductor inside, is from withdrawn from a spool 15 and after going through the shown Process wound on the package 16. The Process of extrusion of the insulating layer 4 and the extrusion of the jacket 5 is not shown here.

The transport direction 19 is indicated by an arrow. When viewed in the direction of transport, the wire initially runs via a deflection roller 20 into a dip pot 17, which has the adhesive 18. Located in the dip pot 17 another deflection roller 20, over which the wire around Is deflected 180 degrees. By the speed of the wire when leaving the dip pot 17, the amount of the funded Adhesive 18 determined.

The wire then runs through an oven 21, which extends longitudinally in the transport direction 19. The oven points one for networking the insulating layer with the adhesive suitable internal temperature. This creates networking on the oven length 22. Before winding on the package 16 passes through the wire several more pulleys 20 and one Cable take-off 23, which consists of two deflection rollers.

Further drying takes place on this route Cooling of the core so that it does not stick when it is wound up.

The extrusion of the jacket 5 can then be carried out in this process then done in a separate process.

Reference symbol list:

1

Ignition wire

2nd

electrical conductor

3rd

Single wire

4th

Insulating layer

5

coat

6

Bonding zone

7

radial direction

8th

axial direction

9

inner overlap zone

10th

outer overlap zone

11

plug

12th

Connector contact

13

grommet

14

Bonding area

15

Spool

16

Package

17th

Diving pot

18th

Adhesive

19th

Direction of transport

20th

Pulley

21

oven

22

Furnace length

23

Cable pull

24th

End side

Claims (13)

1. Ignition cable for motor vehicles having an insulating layer (4) surrounding an electric conductor (2), which insulating layer consists substantially of a polyolefin, and having an outer layer surrounding the insulating layer (4), which outer layer consists substantially of a silicone-organic polymer, characterised in that the insulating layer (4) consists substantially of polyethylene and that the outer layer (5) is stuck to the insulating layer (4) by an adhesive (18) which migrates at least partially into the insulating layer (4) and is anchored therein.
2. Ignition cable according to claim 1, characterised in that the outer layer (5) is at least partially cross-linked with the adhesive (18).
3. Ignition cable according to claim I or 2, characterised in that an adhesion zone (6) between the insulating layer (4) and the outer layer (5) overlaps in the radial direction (7) with an outer zone (10) of the insulating layer (4) and/or with an inner zone (9) of the outer layer (5).
4. Ignition cable according to any one of claims 1 to 3, characterised in that the adhesive (18) is silane based.
5. Ignition cable according to any one of claims 1 to 4, characterised in that the outer layer (5) of the ignition cable (1) is stuck to the end of a sleeve (13) of a plug (11).
6. Ignition cable according to claim 5, characterised in that the sleeve (13) consists substantially of silicone-organic polymer.
7. Method for producing an ignition cable (1) for motor vehicles according to one or several of claims 1 to 6, wherein the insulating layer (4) and the outer layer (5) are extruded, characterised in that an adhesive (18) is applied to the insulating layer (4), that the adhesive (18) is anchored in the insulating layer (4) and that subsequently the outer layer (5) is extruded onto the insulating layer (4).
8. Method according to claim 7, characterised in that a silane-based adhesive (18) is used.
9. Method according to claim 7 or 8, characterised in that the adhesive (18) is applied in a dipping process.
10. Method according to any one of claims 7 to 9, characterised in that an adhesive (18) is cross-linked on the insulating layer (4) by heat treatment.
11. Method according to any one of claims 7 to 10, characterised in that the application of the adhesive (18) and the cross-linking take place continuously in a continuous working process.
12. Method according to any one of claims 7 to 11, characterised in that in the same working process an additional drying process takes place.
13. Method according to any one of claims 7 to 12, characterised in that the outer layer (5) is extruded on at a higher average process rate in a further working process after the cross-linking of the insulating layer (4).

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