DE10360338A1 - Ignition coil for a gasoline engine and method for its production - Google Patents

Abstract

An ignition coil (10) for a gasoline engine with a coil core (12) is proposed, via which at least one winding layer (14) of a first wire coil (16) is wound. At least one winding layer (18) of a second wire coil (20) is again arranged on the first wire coil, an embedding material (22) being arranged between the coil core (12) and the first wire coil (16). The potting material (22) is applied to the inside of the first wire spool (16) and the spool core (12) is inserted into the first wire spool (16) provided with the potting material (22). Furthermore, a method for producing such a pencil ignition coil is given (Figure 1).

Description

The The invention relates to an ignition coil for one Otto engine with a coil core, about which wound at least one winding layer of a first wire coil is. On the first wire coil is again at least one winding layer wound up a second wire coil, wherein between the bobbin and the first wire coil is an embedding material.

Farther The invention relates to a method for producing an ignition coil for one Otto engine.

A ignition coil represents an energy transmitting High voltage source and is used in gasoline engine to control the Spark plug, which in turn ignites the fuel mixture in the combustion chamber of the engine and so the movement of the piston and thus the crankshaft initiates.

A ignition coil consists in principle of two windings of different numbers of turns, the - supported by an iron core or the like coil core - are magnetically coupled together. This refers to the winding with the smaller number of turns as a primary winding and those with the higher ones Number of turns as a secondary winding. The primary serves as a field winding and draws its energy from the car battery, being over an electronic switch controlled by the engine control becomes.

In the secondary winding is then by a targeted interruption in the primary circuit an electrical High voltage generated, which is passed to the spark plug and there leads to a spark.

The primary and the secondary winding are usually concentric on top of each other arranged, with the primary winding Outside, the secondary winding can lie inside. Both windings can also multilayer with appropriate Insulation layers between the individual winding layers both as Chamber, as well as sloping or pilgrim step winding.

A special embodiment of an ignition coil represents a pencil ignition coil which is in direct contact with one within a narrow recess arranged in the engine spark plug stands. For this reason, pencil ignition coils have a relatively small size outer diameter from Z. B. less than 24 mm. Furthermore They should work reliably and typically in a temperature range of about -40 ° C to 160 ° C generate a voltage potential of about 30 kV. To these specifications To cope with are high on the materials to be used Requirements made.

Usually the iron core is embedded for isolation purposes, being more conventional Make a heat shrink tube from a heat-shrinking Thermoplastic over pulled the iron core and shrunk by heat. additionally also a resin is used, which also for further isolation inside the ignition coil Use finds.

disadvantageous However, in this known type of embedding is that different Expansion coefficients of the materials used or an offset between the heat shrink tubing and lead to the iron core in the resin to mechanical stresses. by virtue of These machansichen tensions it often happens that the plastic overstressed becomes and leads to the break or cracks form within the resin. While these Cracks initially only very fine and for the functions of the coil are not significant, the cracks may be due to of material fatigue and thermal cycling stress to the adjacent secondary coil expand. This favors an undesirable partial electrical discharge and material erosion by electrical Discharge or even the occurrence of a short circuit.

There the embedding gap is very narrow and, for example, a width is less than 0.5 mm, due to the tolerances a even education the embedding difficult. The uncertainty in the within the Embedding central alignment of the iron core leads to fluctuations in the Thickness of used filled Potting compound and in the homogeneity of the filler. Consequently, the Material properties not over the entire direction of extension of the iron core or the secondary coil the same. Consequently, there are areas of different thermal and mechanical stress, leaving a risk for the formation of cracks favored becomes. About that In addition, a homogeneous introduction of a filled potting compound in the narrow Embedding gap often difficult to accomplish. It comes easy to the undesirable Formation of cavities or bubbles that are detrimental to the function of the coils can be.

The invention has for its object to provide a pencil ignition coil for a gasoline engine and a method for their production, which or which ensures a homogeneous embedding of the iron core in the potting compound and a relative to the secondary winding central alignment thereof. In addition, the invention Zünd should coil manufacturing technology easy to manufacture and easy to carry out the manufacturing process of the invention.

These Task is followed by an ignition coil Claim 1 or by a method for producing an ignition coil solved according to claim 5. The dependent claims each relate to advantageous developments.

Advantages of invention

Accordingly, that is Embedding material applied to the inside of the first wire coil and the spool core in the first provided with the embedding material Wire coil introduced. A central orientation of the spool core relative to the first wire spool is with these measures guaranteed, there the embedding material on the inside of the first wire coil apply evenly leaves.

Around a particularly high resistance to achieve cracking, the embedding material can Silicone material or the like elastomer, such as. B. a thermoplastic elastomer include. Such materials also ensure good adhesion to the first wire coil.

By doing The embedding material in a liquid state on the inside The first wire winding can be applied, a particularly easy manufacturability the ignition coil achieved in production.

According to one particularly advantageous embodiment can the embedding material on the inside of the first wire winding be splashed. One uses oneself as Injection Mold procedure designated low pressure or high pressure process. This will be a consistent electrical insulation without the appearance of cavities or Bubbles ensured.

Further Advantages and advantageous embodiments of the subject to The invention are the description, the drawings and the claims removed.

drawing

One embodiment The invention is illustrated in the drawing and in the following description explained. Show it:

1 in a schematic side view and in section the structure of a pencil ignition coil; and

2 in a schematic side view and in section a part of the pencil ignition coil.

description of the embodiment

The 1 shows a schematic side view and in section the structure of an ignition coil according to the invention 10 for a gasoline engine. About the coil core 12 , the z. B. is formed as a laminated iron core, is a winding layer 14 a secondary coil 16 wound. Alternatively, the secondary coil 16 also have a plurality of wound layers wound over one another, which can be designed as a chamber or skew winding.

Between the spool core 12 and the secondary coil 16 is an embedding material 22 arranged. The embedding material 22 which comprises a silicone material or the like elastomer, in particular a thermoplastic elastomer, is on the inside of the first wire coil 16 applied. Since such an insulating material can be processed in a liquid state, the embedding material can be 22 with the coil core removed 12 on the inside of the first wire winding 16 clapboard. In this case, a so-called injection molding method is used. The embedding material 22 solidifies and forms an elastic embedding for the spool core 12 that in with the embedding material 22 provided secondary coil 16 is introduced.

Above the secondary coil is again a winding layer 18 the primary coil 20 wound. Also the primary coil 20 may have a plurality of winding layers. Between the primary coil 16 and the secondary coil 20 is an insulation resin, such as an epoxy resin 26 introduced, which is cured by a suitable method.

The entire coil assembly, consisting of the coil core 12 , the secondary coil 16 and the primary coil 20 is in a rod-shaped housing 24 used. Also between the primary coil 20 and the inner wall of the housing 24 is an insulation material 28 brought in. Like in the 1 only indicated, are also the necessary electrical contacts 30 appropriate.

The 2 shows a schematic side view and in section a part of the pencil ignition coil 10 for a gasoline engine. In particular, from the 2 clearly, as the bobbin 12 in the on its inner wall with a thin coating 22 made of an elastomer secondary coil 16 can be introduced.

In an alternative embodiment of the manufacturing method (not shown), the provided with the embedding material secondary coil when inserting the bobbin already be provided with the overlying primary coil.

Of the Iron core can basically embedded in an elastomer with different manufacturing processes being both liquid Materials used as well as solid, such as tubular material inserts can be.

Of the Iron core can additionally with other elements, such. B. on one or both ends attached magnets or additional be pre-assembled axial buffer elements or cover plates.

Claims (14)

Ignition coil ( 10 ) for a gasoline engine with a coil core ( 12 ), over which at least one winding layer ( 14 ) a first wire coil ( 16 ) is wound on which in turn at least one winding layer ( 18 ) a second wire coil ( 20 ) is arranged, wherein between the bobbin ( 12 ) and the first wire coil ( 16 ) an embedding material ( 22 ), characterized in that the embedding material ( 22 ) on the inside of the first wire coil ( 16 ) is applied and the coil core ( 12 ) in the with the embedding material ( 22 ) provided first wire coil ( 16 ) is introduced. Ignition coil according to claim 1, characterized in that the embedding material ( 22 ) comprises a silicone material or the like elastomer, in particular a thermoplastic elastomer. Ignition coil according to claim 1 or 2, characterized in that the embedding material ( 22 ) in liquid to stand can be applied. Ignition coil according to one of claims 1 to 3, characterized in that the embedding material ( 22 ) is injection molded. Method for producing an ignition coil ( 10 ) for a gasoline engine, comprising the following process steps: application of an embedding material ( 22 ) on the inside of the first wire coil ( 16 ); Winding a first wire coil ( 16 ) with at least one winding layer ( 14 ); - Inserting the spool core ( 12 ) in the with the embedding material ( 22 ) provided first wire coil ( 16 ); - winding a second wire coil ( 20 ) with at least one winding layer ( 18 ) over the first wire coil ( 16 ); and - attaching electrical contacts ( 30 ) on the arrangement consisting of coil core ( 12 ), first wire coil ( 16 ) and second wire coil ( 20 ). A method according to claim 5, characterized in that before or during the attachment of the electrical contacts ( 30 ) the arrangement consisting of coil core ( 12 ), first wire coil ( 16 ) and second wire coil ( 20 ) in a housing ( 24 ) is introduced. Method according to claim 5 or 6, characterized in that between the first wire coil ( 16 ) and the second wire coil ( 20 ) an insulation material ( 26 ) is introduced. Method according to one of claims 5 to 7, characterized in that between the second wire coil ( 20 ) and the inner wall of the housing ( 24 ) an insulation material ( 28 ) is introduced. Method according to claim 5 or 7, characterized that the second wire coil is applied to a housing, which at the same time as a winding body accomplished is. Method according to one of claims 7 to 9, characterized in that the step of winding the first wire coil ( 16 ) the application of the insulating material ( 26 ). Method according to one of claims 8 to 10, characterized in that the step of winding the second wire coil ( 20 ) the application of the insulating material ( 28 ). Method according to one of claims 5 to 11, characterized in that as embedding material ( 22 ) a silicone material or the like elastomer, in particular a thermoplastic elastomer is applied. Method according to one of claims 5 to 12, characterized in that the embedding material ( 22 ) is applied in the liquid state. Method according to one of claims 5 to 13, characterized in that the embedding material ( 22 ) is sprayed (injection molded).