JP2013115074A - Ignition coil for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the following problem that: in an ignition coil in which ground potential is secured from a mounting bolt through a ground terminal including a flange for mounting and fixing the ignition plug, if a connection terminal is integrated in the flange part, the amount of an insulating resin in the flange part decreases, and strengh of the flange part is thereby weakened; and since the connection terminal is integrated in the vicinity of a bolt hole of the flange part, a portion where the thickness of the insulating resin is thin is formed at the tip of the flange facing a case body, and there is possibility that the tip of the flange part is broken by vibration caused when mounting the ignition coil and operating an engine.SOLUTION: In the ignition coil for an internal combustion engine that comprises the flange having an almost cylindrical conductive bush formed in a case and a GND terminal inserted into the case, while the GND terminal comprises one end connected to the bush, and the other end electrically connected to an iron core, the one end of the GND terminal is opened at an angle of 60≤θ≤120 in the diameter direction of the bush.

Description

The present invention relates to an ignition coil for an internal combustion engine, and more particularly to the structure of a GND connection terminal.

Conventionally, in an ignition coil for an internal combustion engine, there is a structure having a ground terminal in the connector of the ignition coil in order to remove noise from the iron core and the primary coil. When the terminal is provided, there is a problem that the ignition signal terminal provided in the connector is affected by noise. In order to solve such a problem, the ground potential is secured from the mounting bolt via the ground terminal provided on the flange for mounting and fixing the ignition coil.

However, since such an ignition coil has a structure in which the ground terminal is sandwiched between the mounting bolt and the flange, the ground terminal may be deformed or damaged by the tightening operation of the mounting bolt at the time of mounting. In such a problem, several configurations have been proposed with the goal of preventing the deformation and breakage of the ground terminal by insert molding the ground terminal into the mounting portion of the case. As a typical example of this, for example, Japanese Patent Application Laid-Open No. 2007-198193 (hereinafter “Patent Document 1”) is known.

In the above-mentioned Patent Document 1, an ignition coil for an internal combustion engine includes a primary coil and a secondary coil, an iron core that magnetically couples the two coils, and an insulating case that houses them, and a flange portion of the insulating case. Is fixed to the engine with mounting bolts, and the flange portion has a ground terminal that is grounded to the engine via the bolt or bush. The ground terminal is built in the flange portion and the bolt hole formed in the flange portion. It connects with the engine through a bush installed nearby.

Further, the ground terminal is installed at substantially the center in the thickness direction of the flange portion, and is sandwiched by a conductive bush inserted from above and below at the position of the bolt hole. The bush is inserted through the inner periphery of the bolt hole, and electrical connection with the ground terminal is generated by tightening the mounting bolt. Further, the total thickness of the two bushes and the ground terminal is configured to be slightly thicker than the thickness of the flange portion.

JP 2007-198193 A

However, the conventional ignition coil has the following problems. That is, in the ignition coil of Patent Document 1, the ground terminal is built in the flange portion, and the ground terminal and the engine are electrically connected via a bush installed near the bolt hole formed in the flange portion. Although the mounting bolts are not in direct contact and are prevented from being deformed or broken, when the connection terminal is built in the flange, the strength of the flange decreases due to a decrease in the amount of insulating resin in the flange. .

In addition, since the connection terminal is built in the vicinity of the bolt hole of the flange part, a thin part of the insulating resin is formed at the end of the flange body opposite the case body, and the end of the flange part is damaged due to vibration when the ignition coil is installed or the engine is running. There is a fear. Further, when the flange portion is enlarged in order to maintain the strength of the flange portion, in an ignition coil having a coil portion outside the plug hole, restrictions on mounting the engine further increase.

The present invention has been made in view of the above-described problems, and provides an ignition coil for an internal combustion engine that can secure an insulating resin thickness at a flange tip and prevent breakage without increasing the size of a mounting portion of the ignition coil. The goal is to.

In order to solve the above problems, the present invention is configured as follows. That is, a case, an iron core comprising a central iron core and an outer peripheral iron core in the case, a primary coil in which a primary winding is wound around a primary bobbin, and a secondary winding is wound around a secondary bobbin A rotated secondary coil, a flange having a substantially cylindrical conductive bush formed in the case, a GND terminal inserted in the case, the GND terminal connected to the bush, and the iron An ignition coil for an internal combustion engine comprising an other end electrically connected to the core, wherein the GND terminal is opened at the one end side.

In the above configuration, the one end of the GND terminal may be opened avoiding a portion where the thickness near the tip of the flange is the thinnest, and the one end of the GND terminal is the diameter of the bush. The direction may be opened at an angle of 60 ≦ θ ≦ 120. Further, the one end of the GND terminal may form a holding portion that holds the outer periphery in the radial direction of the bush, or the bush may form a groove portion that fits the holding portion. Further, the GND terminal may be electrically connected to the primary coil and / or an igniter provided in the case.

As described above, a flange having a substantially cylindrical conductive bush formed in the case, a GND terminal inserted into the case, the GND terminal is connected to the bush, and is electrically connected to the iron core. In the ignition coil for an internal combustion engine comprising the ends, one end of the GND terminal opens at an angle of 60 ≦ θ ≦ 120 in the radial direction of the bush, and one end of the GND terminal holds the radial outer periphery of the bush By forming the portion, it is possible to reliably connect the GND terminal and the bushing, and to secure the insulating resin thickness at the flange tip without increasing the size of the ignition coil flange. An ignition coil for an internal combustion engine that can be improved in strength and reduced in size can be realized.

1 is a perspective view of an ignition coil for an internal combustion engine according to a first embodiment of the present invention. It is BB sectional drawing seen from the arrow (A) direction of FIG. 1 is a perspective view of a GND terminal according to a first embodiment of the present invention. It is a perspective view which shows the state which connected the GND terminal and bush which are the 1st Example of this invention. It is sectional drawing which looked at the ignition coil which is 1st Example of this invention from the upper part.

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

FIG. 1 is a perspective view of an ignition coil for an internal combustion engine according to a first embodiment of the present invention, FIG. 2 is a cross-sectional view taken along the line BB of FIG. 1, and FIG. 3 is a perspective view showing a state in which the GND terminal and the bush are connected, and FIG. 5 is a sectional view of the ignition coil as seen from above.

1 to 5, the case 40 forming the outer shape of the ignition coil 80 is formed by box-shaped integral molding having an opening surface on the upper surface in the vertical direction made of insulating resin. Further, the case 40 is formed with a flange 46 for fixing and fixing the ignition coil 80 to an engine head (not shown), and a bolt for fixing the engine head is passed near the tip 46a of the flange 46. The substantially cylindrical bush 52 having conductivity is fixed by insert molding. Further, a connector 44 having a connector terminal 58 for receiving a primary voltage from the battery and an ignition signal from the ECU is formed on the side surface of the case 40.

Further, a high voltage tower 42 having a high voltage terminal 56 for supplying a secondary voltage to the ignition plug is formed on the outer bottom surface of the ignition coil 80 so as to protrude into a plug hole formed in the upper part of the engine. Yes. Furthermore, the outer bottom surface of the case 40 is formed in a mortar shape toward the high-pressure tower 42.

The ignition coil 80 includes an iron core composed of an I-shaped central iron core 20 and a U-shaped outer iron core 22 formed by laminating a plurality of thin plates made of silicon steel plates, and the center A primary coil in which the primary winding 12 is wound about 100 turns around the outer periphery of the primary bobbin 10 molded on the outer periphery of the iron core 20, and a secondary bobbin molded on the outer periphery of the primary coil with resin. It is comprised from the coil part of the secondary coil which wound the secondary winding 16 on the outer periphery of 14 about 8000-15000 turns. Further, the outer peripheral iron core 22 is arranged so that the magnetic path of the iron core is in a direction perpendicular to the opening surface of the case 40.

One of the connecting surfaces of the central iron core 20 and the outer peripheral iron core 22 is provided with a magnet 26 for generating a magnetic flux in the opposite direction to the magnetic flux generated by the primary coil in the magnetic path. Further, one end of the secondary bobbin 14 is provided with a secondary high voltage terminal 60 for supplying a secondary voltage to the high voltage terminal 56, and the other end of the secondary bobbin 14 is provided with 1 from the primary coil. A secondary low voltage terminal (not shown) is provided for receiving the secondary voltage.

The case 40 includes an igniter 30 for supplying an ignition signal to the primary coil. The igniter 30 includes a switching element and a lead frame. The lead frame includes a base, a collector, and an emitter of the switching element. Each has a function as an igniter terminal 32 for connection to the outside. Further, the connector terminal 58 includes a terminal connecting the primary coil and the low voltage side of the secondary coil from the battery, a terminal connecting the igniter terminal 32 disposed on the base side of the igniter 30 from the ECU, The igniter 30 is composed of a total of three terminals that are connected to the ground from the igniter terminal 32 arranged on the emitter side.

Further, the igniter terminal 32 and the connector terminal 58 have substantially flat metal terminals, and two of the igniter terminal 32 and the connector terminal 58 are led out in the same direction, and electrically between each of them. They are connected using welding so as to realize conduction. Further, the igniter terminal 32 and the connector terminal 58 are led out in a direction perpendicular to the opening surface of the case 40, and the connector terminal 58 extends over the inner wall of the case 40 on the same surface as the connector 44 formed on the case 40. Are arranged.

Further, a stainless steel GND terminal 50 that connects the bush 52 to the coil housing portion of the case 40 in the flange 46 of the case 40 is provided by insert molding. Further, one end 51a of the GND terminal 50 forms a holding portion 50a for holding the radially outer peripheral surface of the bush 52, and the holding portion 50a is configured to receive the coil of the case 40 with the center of the bush 52 as an axis. The outer periphery of the bushing 52 is sandwiched by opening 120 degrees in the direction of the tip end 46a of the flange 46 from the portion.

The other end 51b of the GND terminal 50 is disposed on the same plane as the flange 46 of the case 40. Further, the case 40 includes a connection terminal 54 that electrically connects the other end 51b of the GND terminal 50 to the central iron core 20 and the outer peripheral iron core 22.

Further, a protrusion is formed on a connection surface of the connection terminal 54 with the central iron core 20 and the GND terminal 50, and the connection terminal 54 is in line contact with the central iron core 20 and the GND terminal 50. . Further, the periphery of the outer peripheral iron core 22 excluding the connection surface with the central iron core 20, the magnet 26, and the connection terminal 54 is covered with an iron core cover 24 formed of polybutylene terephthalate.

Further, the connection terminal 54 is insert-molded in the iron core cover 24, and is electrically connected to and held by the outer peripheral iron core 22.

The case 40 is filled with a mold resin 70 that realizes electrical insulation of the ignition coil 80 and physical fixation of each member. Further, the mold resin 70 is filled to the vicinity of the opening surface of the case 40, and the iron core, the primary coil, and the secondary coil are lower than the resin surface 72 formed near the opening surface of the case 40. Provided in position.

With the above configuration, the GND terminal 50 is provided by insert molding in the flange 46 of the case 40, the one end 51a of the GND terminal 50 is connected to the bush 52, and the other end 51b is electrically connected to the iron core. Since the potential of the iron core is dropped to the ground via the GND terminal 50 and the bush 52, a shielding effect against noise generated during operation of the ignition coil 80 can be obtained.

Further, the one end 51a of the GND terminal 50 forms the holding portion 50a for holding the outer periphery in the radial direction of the bush 52, and the holding portion 50a opens 120 degrees on the tip end 46a side of the flange 46. By sandwiching the outer periphery of the bush 52, the GND terminal 50 and the bush 52 can be reliably connected, and conventionally, the three-layer structure of the bush 52, the holding portion 51a, and the flange 46 is used. However, since the bush 52 and the flange 46 have a two-layer structure, the risk of breakage of the flange 46 can be reduced due to the difference in thermal expansion coefficient of each member. Further, as shown in FIG. 5, the holding portion 50 a of the GND terminal 50 does not reach the distal end portion 46 a side of the flange 46, and the length t is from the bush 52 to the distal end portion 46 a of the flange 46. In addition, the length of the dimension l from the bush 52 to the bent portion near the front end portion 46a of the flange 46 can be secured, and the resin thickness of the front end portion 46a of the flange 46 is increased. Since the strength of the flange 46 can be improved, the flange 46 can be downsized.

As a modification of the first embodiment, the shapes of the case 40, the flange 46, the connector 44, and the high-pressure tower 42 may be appropriately changed depending on design circumstances. Further, the shapes of the central iron core 20 and the outer peripheral iron core 22 may be appropriately changed according to design circumstances, and the outer iron core 22 has a magnetic path of the iron core parallel to the opening surface of the case 40. The outer peripheral iron core 22 may be partly exposed from the case 40. Further, the shape of the bush 52 may be arbitrarily changed according to design circumstances, or a groove portion for fitting the holding portion 50a of the GND terminal 50 may be formed on the radially outer peripheral surface of the bush 52. A protrusion may be formed on the radially outer peripheral surface of the bush 52 to prevent the bush 52 from falling off the flange 46.

Further, the GND terminal 50 may be formed of a conductive material other than stainless steel, and the shape of the other end 51b of the GND terminal 50 that contacts the connection terminal 54 may be an arbitrary shape depending on design circumstances. The other end 51b of the GND terminal 50 may be in direct contact with the central iron core 20 and / or the outer peripheral iron core 22 without the connection terminal 54 interposed therebetween. Further, the shape of the holding portion 50a of the GND terminal 50 may be changed to an arbitrary shape according to design circumstances, and the holding portion 50a has an angle of the flange 46 on the tip end portion 46a side of 60 ≦ θ ≦ 120. The holding portion 50a may be opened at an angle at which the outer periphery of the bush 52 can be sandwiched.

The angle at which the one end 51a side of the GND terminal 50 is opened is arbitrary as long as the holding portion 50a avoids the portion of the flange 46 where the resin thickness in the vicinity of the tip end portion 46a is the thinnest. The angle may be appropriately changed. Further, the GND terminal 50 may be connected to a terminal connecting the ground from the igniter terminal 32 disposed on the emitter side of the primary coil and / or the igniter 30. Further, the GND terminal 52 and the bush 52 may be inserted after being connected by welding or the like before the case 40 is formed.

10: 1 primary bobbin
12: Primary winding
14: Secondary bobbin
16: Secondary winding
20: Central iron core
22: Outer iron core
24: Iron core cover
26: Magnet
30: Igniter
32: Igniter terminal
40: Case
42: High-pressure tower
44: Connector
46: Flange
46a: Tip
50: GND pin
50a: Holding part
51a: one end
51b: The other end
52: Bush
54: Connection terminal
56: High voltage terminal
58: Connector terminal
60: Secondary high-voltage terminal
70: Mold resin
72: Resin surface
80: Ignition coil

Claims (6)

Case and
An iron core comprising a central iron core and an outer peripheral iron core in the case, a primary coil in which a primary winding is wound around a primary bobbin, and a secondary coil in which a secondary winding is wound around a secondary bobbin When,
A flange having a substantially cylindrical conductive bush formed on the case;
A GND terminal inserted in the case;
The GND terminal is an ignition coil for an internal combustion engine including one end connected to the bush and the other end electrically connected to the iron core.
An ignition coil for an internal combustion engine, wherein the GND terminal opens at the one end side. 2. The ignition coil for an internal combustion engine according to claim 1, wherein the one end of the GND terminal is opened to avoid a portion where the thickness near the tip of the flange is the thinnest. 3. The ignition coil for an internal combustion engine according to claim 1, wherein the one end of the GND terminal is opened at an angle of 60 ≦ θ ≦ 120 in the radial direction of the bush. The ignition coil for an internal combustion engine according to any one of claims 1 to 3, wherein the one end of the GND terminal forms a holding portion for holding a radially outer periphery of the bush. The ignition coil for an internal combustion engine according to claim 1, wherein the bush forms a groove portion into which the holding portion is fitted. 6. The ignition coil for an internal combustion engine according to claim 1, wherein the GND terminal is electrically connected to the primary coil and / or an igniter provided in the case.

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