JP5291978B2 - Ignition coil for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce connection defects by suppressing corrosion of a connection terminal portion of an electric conductor and a conductive bush since a conventional ignition coil for internal combustion engine has a conductive metal bush and an electric conductor, connected to the conductive bush, electrically connected to each other on an upper surface of the conductive bush positioned outside a coil case and then an interface of the electric connection portion is in the atmosphere, so there is a risk of a connection defect due to corrosion of the connection terminal portion of the electric conductor and the conductive bush. <P>SOLUTION: The coil case is formed by molding the electric connection portion of the electric conductor, connecting the conductive bush coming into contact with an electric ground potential portion to a power supply ground terminal of a connector provided in the coil case, of resin in one body inside a resin molding forming the coil case. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an ignition coil for an internal combustion engine that supplies a high voltage for generating a spark discharge to an ignition plug of the internal combustion engine.

  In this type of ignition coil, an iron core around which a primary coil and a secondary coil are wound is housed in a coil case, and an electrically insulating resin is injected between each member in the coil case to be cured.

  However, the iron core having the above structure is in an electrically floating state within the coil case, and a shielding effect against radiation noise generated during coil operation cannot be expected.

  In recent years, electronic control has been a branching component around the engine, and it is necessary to reduce noise in an ignition coil that is one of the sources of noise.

  As a measure for reducing the noise of the ignition coil, Japanese Patent Application Laid-Open No. 2005-50892 describes that an iron core is connected to an engine head via a conductive metal bush provided in a coil case.

JP 2005-50892 A

  However, in the above prior art, the conductive metal bush and the electric conductor connected to the conductive metal bush are electrically connected on the upper surface of the conductive bush located outside the coil case.

  For this reason, the interface of the electrical connection portion exists in the atmosphere, and the connection terminal portion of the electrical conductor and the conductive bush may corrode and cause poor connection.

  In addition, in the connection structure in which the connection terminal of the electric conductor is sandwiched between the bolts for attaching the coil, an external force (rotational force) is applied to the connection terminal portion when the bolt is tightened, so the connection terminal of the electric conductor is shifted from the initial position, It is conceivable that a conduction failure may occur, and a stable electrical connection can be achieved.

  An object of the present invention is to reduce the connection failure by suppressing the corrosion of the connection terminal portion of the electric conductor and the conductive bush.

  Preferably, at the time of connection, the connection terminal of the electric conductor is less likely to receive an external force, and connection failure is less likely to occur.

In order to achieve the above object, in the present invention, the electrical connection portion of the electrical conductor for connecting the conductive bush that contacts the coil case to the electrical ground potential portion and the power supply ground terminal of the connector provided in the coil case, The resin is integrally molded inside the resin molded body forming the coil case. Specifically, the other end of the electric conductor having one end connected to the power supply ground terminal provided in the connector is electrically connected to the metal bush at the outer periphery of the metal bush that is fixed to the electric ground potential portion with a bolt. Configured to connect to.

  According to the present invention configured as described above, the electrical connection portion of the electrical conductor and the conductive bush can be protected from corrosion, and a highly reliable electrical connection structure is possible.

Further, according to the present invention, it is difficult for an external force to act on the electrical connection portion of the electrical conductor, thereby reducing connection failure.

  An embodiment of the present invention will be described with reference to FIGS.

  The ignition coil has an iron core 3 for magnetically coupling the primary coil 1, the secondary coil 2, the primary coil 1 and the secondary coil 2 to generate a high voltage, and the iron core 3 is a side iron core 3a. The center iron core 3b is wound with the primary coil 1 and the secondary coil 2, and the side iron core 3a is annularly arranged so as to surround the primary coil 1 and the secondary coil 2. The The coil case 4 is made of a thermoplastic resin (for example, PBT), accommodates a coil assembly composed of a primary coil, a secondary coil 2, and an iron core 3, and is insulated to provide electrical insulation in the gaps between the members. Resin 5 (for example, epoxy resin) is filled to form a coil portion. The high voltage generated by the coil is energized to the spark plug 7 via the spring 6.

  The ignition coil is fixed to the engine head 10 by attaching a tightening bolt 9 to a conductive bush 8 provided on the outer periphery of the coil case 4. A connection terminal A11 formed of a conductive member is electrically connected to the conductive bush 8 by welding (or a conductive adhesive) inside the coil case. The connected conductive bush 8 and connection terminal A11 can be electrically connected inside the coil case resin by being inserted into the coil case when the coil case is molded. Further, the other end side of the connection terminal A11 is electrically connected to the side iron core 3a, so that the iron core 3 is grounded. As a result, the radiation noise generated during the coil operation is arranged so that the side iron core 3a in the ground state surrounds the coil, so that the shielding effect works and the noise can be reduced. The iron core 3 is also electrically connected to the GND terminal 13 of the connector by a connection terminal B12 formed of a conductive member, and the conduction noise from the connector harness is grounded iron core 3, the connection terminal A11. The noise is reduced to the engine head through the conductive bushing 8.

  Next, another embodiment of a method for connecting the connection terminal A and the conductive bush will be described with reference to FIGS.

  In the connection structure in FIG. 3, a hole is formed at the end of the connection terminal A11 formed in a plate shape, a plurality of protrusions 11a are formed inside the hole, and the outer periphery of the conductive bush is press-fitted into the protrusion 11a. This is a method for achieving electrical connection. The conductive bush 8 is provided with a stopper function at the time of press-fitting by forming a stepped portion 8a, and by increasing the contact area with the coil case resin portion, the holding strength with the coil case is improved. Yes. This makes it possible to prevent the conductive bushing 8 from co-rotating against the rotational force received when the bolt 9 is tightened. Further, when the connection terminal A11 and the conductive bush 8 are press-fitted, the protrusion shape may be formed on the conductive bush side. For example, in order to increase the holding force of the conductive bush 8 with the coil case, a plurality of grooves may be formed in the outer diameter portion of the conductive bush, and it is also effective to press-fit using this protrusion (groove). It becomes a means.

  The connection structure in FIG. 4 is a method of achieving electrical connection by forming a C shape at the end of the connection terminal A11 and fitting the conductive bush 8 into the C shape portion.

  The connection structure in FIG. 5 is a method of achieving electrical connection by forming the end portion of the connection terminal A11 formed in a line shape in a spring shape and lightly press-fitting a conductive bush into the inner diameter portion of the spring. An inexpensive structure can be obtained by forming the connection terminal A11 with a wire.

  Further, since the connection terminal is inserted into the flange of the coil case, the strength of the flange portion is increased, and the vibration resistance can be improved.

  It is as follows when the aspect of an Example is summarized.

Embodiment 1
Insulating resin for containing a core that forms a closed magnetic path with a gap and a primary coil and a secondary coil wound around the outer periphery of the core in a coil case and electrically insulating gaps between the members. In the ignition coil filled with, the iron core is electrically connected to a grounded conductive engine head and a GND terminal of a connector provided in the coil case for supplying power from a battery. An ignition coil for an internal combustion engine.

Embodiment 2
A conductive bush provided on the outer periphery of the coil case for fixing the ignition coil to the engine head is electrically connected via a connection terminal A formed of a conductive material, and the iron core and the connector The ignition coil for an internal combustion engine according to the first embodiment, wherein the GND terminal has a structure in which the GND terminal is electrically connected via a connection terminal B formed of a conductive material.

[Embodiment 3]
The ignition for an internal combustion engine according to the first and second embodiments, wherein the conductive bush and the connection terminal A are electrically connected inside a resin to which the conductive bush in the coil case is fixed. coil.

Embodiment 4
The ignition coil for an internal combustion engine according to any one of embodiments 1 to 3, wherein the conductive bush and the connection terminal A are electrically connected by welding or a conductive adhesive and are inserted into the coil case when the coil case is formed.

[Embodiment 5]
The conductive bush and the connection terminal A are provided with a hole at the tip of the connection terminal A formed in a plate shape, a plurality of protrusions are formed inside the hole, and the outer periphery of the conductive bush is press-fitted into the protrusion. An ignition coil for an internal combustion engine according to the first to third embodiments, wherein the ignition coil is electrically connected to be inserted into the coil case when the coil case is formed.

[Embodiment 6]
The conductive bush and the connection terminal A are formed in a C-shape at the tip of the connection terminal A, and are electrically connected by fitting the conductive bush into the C-shaped portion. An ignition coil for an internal combustion engine according to any one of embodiments 1 to 3, wherein the ignition coil is inserted into the internal combustion engine.

[Embodiment 7]
The conductive bush and the connection terminal A are formed in a coil shape by forming the tip of the connection terminal A, which is formed in a linear shape, into a spring shape, and lightly press-fitting the conductive bush into the inner diameter portion of the spring. An ignition coil for an internal combustion engine according to Embodiments 1 to 3, wherein the ignition coil is inserted into a coil case during molding.

The whole longitudinal cross-sectional view of the ignition coil for internal combustion engines. An example of the connection structure of the terminal of an electrical conductor and a conductive metal bush. Another embodiment of a connection structure between a terminal of an electric conductor and a conductive metal bush. Another embodiment of a connection structure between a terminal of an electric conductor and a conductive metal bush. Another embodiment of a connection structure between a terminal of an electric conductor and a conductive metal bush.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Primary coil 2 Secondary coil 3 Iron core 3a Side iron core 3b Center iron core 4 Coil case 5 Insulation resin 6 Spring 7 Spark plug 8 Conductive bushing 8a Stepped part 9 Tightening bolt 10 Engine head 11 Connection terminal A
11a Protrusion 12 Connection terminal B
13 GNG terminal

Claims (5)

An ignition coil device including an ignition coil for supplying a high voltage to an ignition plug of an internal combustion engine, comprising a coil case formed of a resin molded body,
The coil case is integrally molded with a connector having a terminal for connecting the ignition coil to a power source, a power source ground or an external circuit,
Furthermore, the coil case has a conductive metal bush that contacts the member having the ground potential, and has a hole through which a bolt for fixing the ignition coil device to the member having the ground potential is inserted. Metal bushes that are fastened and fixed together are resin molded together,
The other end of the first electrical conductor having one end connected to the power ground terminal provided in the connector is electrically connected to the iron core, and the other of the second electric conductor having one end connected to the iron core. The end is electrically connected to the metal bush at the outer periphery of the metal bush,
The ignition coil for an internal combustion engine, wherein the second electric conductor and its connecting portion are integrally resin-molded inside the resin molded body forming the coil case together with the metal bush and the connector. In claim 1,
The connecting portion is an ignition coil for an internal combustion engine is a connection portion between the metal bushing and the second electrical conductor. In the one according to claim 1 or 2 ,
The other end of the second electric conductor is formed in a plate shape, and a hole is provided in the plate-like portion, and a plurality of protrusions protruding radially inward are provided inside the hole. An ignition coil for an internal combustion engine in which the projection is press-fitted into the outer periphery of the metal bush to form an electrical connection, and the connection is insert-molded in the resin molded body of the coil case . In the one according to claim 1 or 2 ,
A semi-annular plate-like portion is formed at the other end of the second electric conductor , and the semi-annular plate-like portion is fitted into the outer periphery of the metal bush to constitute an electrical connection portion, An internal combustion engine ignition coil in which the connecting portion is insert-molded in the resin molded body of the coil case. In the one according to claim 1 or 2 ,
A string winding portion is formed at the other end of the second electrical conductor , and the string winding portion is wound around the outer periphery of the metal bush to constitute an electrical connection portion, and the electrical connection portion is An ignition coil for an internal combustion engine, which is insert-molded in the resin molded body of the coil case.

Images