JP4732742B2 - Ignition coil - Google Patents

Description

  The present invention is an ignition coil of an ignition device for an internal combustion engine, provided with a coil casing made of insulating plastic, provided with an I-core that works magnetically, and supplied by the I-core. Surrounded by a first coil winding connected to the voltage and a second coil winding connected to the high voltage connection, forming a magnetic circuit with the I core, The present invention relates to a type in which a peripheral core is provided surrounding a device composed of one coil winding and a second coil winding.

  Such ignition coils are known in practice, in particular for controlling one ignition plug (Kompaktzuendspule) or at least two ignition plugs for an automotive internal combustion engine working according to the Otto principle. A multi-spark coil (Mehrfunkenspule) is also formed. The ignition coil forms an energy store / transformer. This energy store and transformer converts the relatively low supply voltage electrical energy normally provided by the associated automotive DC voltage mounted power source into magnetic energy. This magnetic energy is converted into a high voltage pulse at the desired time when it is desired to have the ignition pulse delivered to a spark plug that serves to ignite the fuel mixture in the combustion chamber of the internal combustion engine.

  Known compact ignition coils usually have a coil casing made from plastic. A so-called I-Kern that works magnetically and is made of a ferromagnetic material such as iron is disposed in the coil casing. The I-core may be formed in a rectangular parallelepiped shape or a rod shape, for example, and a first so-called primary winding connected to a DC voltage-mounted power source, that is, a supply voltage, and a second so-called second connected to a spark plug. Surrounded by the next winding. Both windings are typically made from copper wire. The known compact ignition coil further has a so-called surrounding core (Umfangskern) or O-core (O-Kern), which is also made of a ferroelectric material. This peripheral core or O core forms a magnetic circuit with the I core and surrounds the device consisting of the primary and secondary windings.

  Converting the voltage supplied by the DC power supply of an automobile into a high voltage means that a current flows through the primary winding, thereby having a predetermined direction around the primary winding and closing itself. This is done so that a magnetic field is generated. In order to release the stored electrical energy as high voltage pulses, the formed magnetic field is forced to change direction by interrupting the current. This creates a high voltage in the secondary winding that is formed near the primary winding and has a much larger number of windings. Due to the conversion of electrical energy in the spark plug, the pre-formed magnetic field collapses. The ignition coil is discharged. The high voltage, spark current and spark duration during ignition of the fuel mixture supplied into the combustion chamber of the internal combustion engine can be adapted to the respective requirements, depending on the design of the secondary winding.

  In particular, in the case of a compact ignition coil, air gaps exist between the O core and the ignition coil casing on the surfaces of the ignition coil casing located on opposite sides of each other. A partial discharge of the O core may occur through this air gap. This partial discharge is caused by an electric field generated between the O core and the ignition coil casing. The narrower the air gap, the greater the dominant electric field. This can also lead to a stronger partial discharge and material consumption of the ignition coil casing of the ignition coil or other adjacent components, i.e., materialabbau. Therefore, in the past, in order to prevent partial discharge, there has always been an effort to make the air gap between the O core and the ignition coil casing as large as possible.

  For design reasons, especially in the design of small compact ignition coils, the air gap between the O-core and the ignition coil casing is designed to be large enough to ensure sufficient durability of the ignition coil (Dauerlaufbestaendigkeit). It may not be possible anymore. This is due to the smallest air gap between the nics umspritzt O core and the coil casing. This air gap is caused by inadequate adhesion of the O-core to a casing made from plastic. This also causes a high potential difference and an accompanying partial discharge of the O core.

  The object of the present invention is to provide an ignition coil of the type mentioned at the outset, in which sufficient resistance to sustained operation is ensured.

  In order to solve this problem, in the configuration of the present invention, at least one conductive plastic section is disposed at least partially between the coil casing and the surrounding core, and the plastic section is electrically connected to the surrounding core. Connected to the coil casing with almost no air gap.

  2. An ignition coil according to the invention of an ignition device for an internal combustion engine of the type defined in the superordinate concept part of claim 1, wherein at least partly at least one conductive plastic section between the coil casing and the surrounding core. The ignition coil, in which the plastic section is electrically connected to the surrounding core and is adjacent to the coil casing without an air gap, has the following advantages. That is, at least in the region where the at least one plastic section is arranged, an electric field acting via air cannot occur between the surrounding core or O-core and the coil casing, and thus the region Then, neither the partial discharge of the O core through the coil casing nor the reduction of the material occurs. Rather, only a reduced partial discharge occurs through the shortest air section provided between the O core and the coil casing. Moreover, the air section is configured to be extended and moved to the outside by the conductive plastic section as compared with the above-mentioned known prior art ignition coil in which a predetermined air gap exists between the O core and the coil casing. Has been. The O core or surrounding core and the conductive plastic section are at the same potential.

  The conductive plastic section may be coupled to a coil casing made from plastic by use of an injection molding method. As a result, no air gap is formed between the two structural members. For example, the coupling part may be such that the at least one conductive plastic section is first anchored by injection molding in the peripheral core, and then the peripheral core with the conductive plastic section is embedded in the coil casing by injection molding. Can be formed as eingespritzt.

  That is, the conductive plastic section electrically removes the air gap between the surrounding core of the ignition coil and the insulating plastic component, in particular the coil casing.

  In an advantageous embodiment of the ignition coil according to the invention, the electrically conductive plastic section at least partially covers the inner surface of the surrounding core, and advantageously at least excessive material consumption can lead to failure of the ignition coil. It is covered with a certain point.

  The conductive plastic section has a thickness of, for example, 0.1 mm to 2.5 mm, preferably about 0.5 mm. However, it is also possible to make the conductive plastic section thinner and to adhere to the surrounding core or casing in the form of a thin conductive plastic layer, optionally partly formed.

  In a special embodiment of the ignition coil according to the invention, the conductive plastic section has a substantially U-shaped cross section. After embedding the surrounding core with plastic section in the coil casing by injection molding, the base area of the conductive plastic section is spaced from the surrounding core via a minimum air gap due to production technology. It may be placed. On the other hand, the side surface of the plastic section is in contact with the surrounding core and forms an electrical connection necessary for potential compensation. In other words, the conductive plastic section is arranged in the form of a clip on the inner surface of the surrounding core and is formed as a plastic body.

  Further advantages and advantageous configurations of the object according to the invention are indicated in the description, the drawings and the claims.

  Embodiments of the ignition coil according to the invention are schematically illustrated in the drawing and will be described in detail below.

  Illustrated in the drawing is an ignition coil 10 of an internal combustion engine ignition device (not shown otherwise) designed as an automobile Otto engine. The ignition coil 10 serves to supply a high voltage pulse to a spark plug (not shown). As a result, the air / fuel / air mixture contained in the combustion chamber of the internal combustion engine can be ignited.

  The ignition coil 10 configured as a compact ignition coil has a casing 12. The casing 12 is made of an electrically insulating plastic 12. A soft magnetic, rectangular parallelepiped I-core 14 is arranged at a central position in the casing 12. The I-core 14 is made of a paketiert metal sheet or a laminated electric metal sheet.

  An insulator 16 made of plastic is disposed around the magnetically acting I core 14. The insulator 16 serves as a coil body for a so-called primary winding 18 formed of a copper wire. The primary winding 18 is connected to the DC voltage-mounted power source of the automobile via the low voltage connection portion 20. Therefore, a DC voltage of 12 V, for example, can be supplied to the primary winding 18.

  The primary winding 18 is surrounded by a second coil body 21 disposed concentrically. A so-called secondary winding 22 formed of a copper wire is wound around the coil body 21. This secondary winding 22 is connected to a high voltage connection 24 that can be connected to the associated spark plug of the ignition coil 10.

  The I core 14, the primary winding 18, the coil body 21, and the secondary winding 22 form one constituent unit. This constituent unit is embedded in a cast resin product (not shown) by casting and is thus fixed in position in the casing 12.

  The casing 12 is further surrounded by a so-called peripheral core or O core 26 at the height of the I core 14. The O core 26 is also made of a bundled metal thin plate or a laminated electric metal thin plate, and is connected to the I core 14 to form a magnetic circuit. On the side opposite to the low voltage connection 20, the O core 26 has a screw eye 27. This screwing eye 27 serves for ground connection.

  The O-core 26 has a substantially square profile and has a plastic section 28 formed on its inner surface from a conductive plastic. The plastic section 28 has a generally U-shaped profile and a generally U-shaped cross section. The side surfaces of the plastic section 28 are connected to the O-core 26 in a form-connecting manner (formschluessig). This ensures an electrical contact connection between the O core 26 and the plastic section 28. The plastic section 28 is spaced from the O core 26 in the region of its base, i.e., on the inner surface of the O core 26, due to fabrication, with a minimum air gap.

  The plastic section 28 secured to the O-core 26 by injection molding has a thickness of, for example, about 0.5 mm and is connected to the casing 12 in a shape connection, ie without an air gap.

  Alternatively, the conductive plastic section 28 may be formed as an independent plastic body, for example, locked to the inner surface of the O core 26 as a prefabricated clip.

  Similarly, the plastic section 28 may be produced as a plastic layer, for example by means of vapor deposition or electroplating, and formed in the casing or the surrounding core.

It is a top view of the ignition coil by this invention.

2 is a cross-sectional view of the ignition coil according to FIG. 1 taken along the line II-II in FIG.

FIG. 5 is a perspective plan view of an ignition coil O-core with a conductive plastic section.

Explanation of symbols

  10 ignition coil, 12 casing, 14 I core, 16 insulator, 18 primary winding, 20 low voltage connection, 21 coil body, 22 secondary winding, 24 high voltage connection, 26 O core, 27 screwed eye , 28 Plastic classification

Claims (7)

An ignition coil of an ignition device for an internal combustion engine, which is provided with a coil casing (12) made of insulating plastic, and is provided with a magnetically acting I core (14). 14) is surrounded by a first coil winding (18) connected to the supply voltage and a second coil winding (22) connected to the high voltage connection, and the I core (14) And a surrounding core (26) surrounding the device comprising a first coil winding (18) and a second coil winding (22). In one type, at least one conductive plastic section (28) is disposed at least partially between the coil casing (12) and the surrounding core (26), the plastic section (28) being Electrically connected to surrounding core Have been, almost without air gap is adjacent to the coil casing (12), the conductive plastic section (28) has a cross section substantially U-shaped, its side shape connected to the Ignition coil, characterized in that it is connected to the surrounding core .   The ignition coil of any preceding claim, wherein the conductive plastic section (28) at least partially covers the inner surface of the surrounding core (26). The ignition coil according to claim 1 or 2 , wherein the conductive plastic section (28) is arranged in the peripheral core (26). The ignition coil according to claim 1 or 2 , wherein the conductive plastic section (28) is arranged in the casing (12). Conductive plastic section (28) has a thickness of 0.1Mm～2.5Mm, any one ignition coil as claimed in claims 1 to 4. Conductive plastic section (28) is formed as a plastic material, any one ignition coil as claimed in claims 1 to 5. Conductive plastic section (28) is formed as a plastic layer, any one ignition coil as claimed in claims 1 to 5.

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