JPH06147088A - Ignition coil unit - Google Patents

Abstract

PURPOSE:To improve the ignition voltage detecting accuracy in enlarging the capacitance of a capacitor and prevent any corona discharge due to abnormal access and contact of the electrodes of the capacitor and a leakage current from occurring in installing the ignition voltage detecting capacitor in an ignition coil unit to judge a misfire in a spark-ignition type internal combustion engine. CONSTITUTION:An electrode 13 to be conducted to the output end of a secondary coil 8 is installed in an outer position of this coil 8 in a case 9 of an ignition coil unit 3 in a cantilever supporting state from the vicinity of an end part at the high tension side of the secondary coil, and a counter electrode 14 is installed in parallel with the electrode 13, constituting a capacitor 15 for detecting an ignition voltage between the electrode 13 and the counter electrode 14, and then a partition wall part 21 consisting of hard insulating material is installed in the point midway between both these electrode 13 and 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for detecting misfire during operation of a spark ignition type internal combustion engine such as a gasoline engine, and an ignition coil device for an engine ignition system. Is related to the structure of.

[0002]

2. Description of the Related Art As is well known, in a spark ignition type internal combustion engine such as a gasoline engine, a high voltage generated by an ignition coil is distributed to each cylinder by a distribution means such as a distributor and is given to a spark plug of each cylinder. The spark discharge between the electrodes of the spark plug ignites the fuel-air mixture drawn into the combustion chamber of each cylinder, causing combustion.
In such an ignition / combustion process of the internal combustion engine, a phenomenon that combustion of the fuel mixture is not normally performed, that is, misfire may occur for some reason. The causes of such misfire are roughly classified into those caused by the fuel system and those caused by the ignition system. The former misfire caused by the fuel system is caused by lean or rich fuel mixture, and is a phenomenon in which spark discharge occurs between the electrodes of the spark plug but the fuel mixture is not ignited. On the other hand, the latter misfire caused by the ignition system is a phenomenon in which normal spark discharge does not occur due to fogging of the electrode of the spark plug or abnormality of the ignition circuit.

If a misfire occurs during operation of the internal combustion engine, not only the operating performance is deteriorated but also the fuel consumption is deteriorated, and further, the afterfire of unburned gas in the exhaust system passage adversely affects the exhaust gas purifying device and the like. And other problems occur. Further, once the misfire has occurred, it means that the fuel system or the ignition system has inconvenience such as a misadjustment or a failure. Therefore, it is necessary to avoid leaving the misfire. Therefore, recently, it has been strongly desired to develop a device that immediately detects a misfire when it occurs.

One type of misfire detection device that has been proposed in the past is the mis-spark detection device disclosed in Japanese Patent Laid-Open No. 52-118135. This miss spark detector
As shown in FIG. 6, a conductor 51 is wound around the outer periphery of the high-voltage cord 50 of the engine ignition system to form a detection capacitor (a kind of capacitance probe) 52 having the insulating coating 50A of the high-voltage cord 50 as a dielectric. In addition, the voltage dividing capacitor 53 is connected between the detecting capacitor 52 and the ground, and the detecting capacitor 52 is caused by the ignition voltage (secondary voltage of the ignition coil) applied to the conductive core wire 50B of the high voltage cord 50. A voltage is induced between both electrodes of the detection capacitor 52 by the electrostatic capacitance of
The induced voltage is electrostatically divided by the detecting capacitor 52 and the voltage dividing capacitor 53, and the voltage (divided voltage) across the voltage dividing capacitor 53 is used as a detected voltage to the electronic circuit 54 for signal processing and determination. The occurrence of the mis-spark is determined by utilizing the fact that the waveforms of the sent-in and ignition voltages are different between when the normal spark discharge is generated and when the spark discharge is not generated (during the mis spark). Therefore, the above-mentioned proposed apparatus detects misfire among misfires, especially when spark discharge does not occur due to the ignition system.

On the other hand, the applicant of the present application has already filed Japanese Patent Application No. 3-326.
No. 509 proposes a misfire detection device for an internal combustion engine. This misfire detection device detects the ignition voltage from the high voltage cord of the ignition system by electrostatic partial pressure similarly to the above, and even if spark discharge is performed at the spark plug, the ignition voltage waveform is normal combustion and normal combustion. The misfire caused by the fuel system is determined and detected by utilizing the fact that it is different from the case in which the occurrence of no.

As described above, in the conventional misfire detection device, as a means for detecting the ignition voltage, a belt-shaped or plate-shaped conductor is wound around the outer periphery of the high-voltage cord of the ignition system, and the conductor and the high-voltage cord. It was usual to use a so-called capacitance probe in which a detection capacitor having an insulating coating of a high voltage cord as a dielectric was formed between the core wire and the core wire. However, in general, the high-voltage cord is flexible and elastic and is easily vibrated. Moreover, the high-voltage cord is easily affected by ambient humidity changes, water wetting, oil stains, dust, etc. When the detection capacitor is formed by winding the electric conductor of (1), the capacitance is likely to change due to such positional displacement due to mechanical vibration, humidity change, water wetting, or oil or dust. A slight change in capacitance does not hurt if it is merely to confirm the ignition voltage, but when determining a misfire, it is generally necessary to accurately detect the voltage waveform. If the capacitance changes, the detected voltage waveform deteriorates, and it may not be possible to reliably determine misfire.

Further, the insulating coating of the high-voltage cord is generally made of synthetic rubber, but the rubber is easily deteriorated by heat, oil stains, etc. Therefore, when a conductor is wound around the outer periphery of the high-voltage cord to form a detecting capacitor. In addition to the change in the capacitance over time due to the deterioration of the insulation coating, the electrical insulation is likely to be destroyed, in which case a high-voltage leak voltage causes the conductor to form the detection capacitor. In addition, there is a possibility that this leak voltage may be guided to the electronic circuit portion of the misfire detection device, resulting in failure or malfunction of the electronic circuit portion.

Further, it is quite troublesome in practice to securely attach and fix the conductor to form the detecting capacitor on the insulating coating of the flexible and elastic high-voltage cord, and it is difficult to maintain. There is also a problem that requires considerable effort.

In order to solve the above problems, the inventors of the present application have already proposed, in Japanese Patent Application No. 4-136249, a conductor for forming a capacitor for detecting an ignition voltage.
The structure provided in the resin integrally molded with the ignition coil is proposed.

Specifically, the ignition coil structure proposed above has an iron core, a primary coil and a secondary coil wound around the iron core, and a primary side connector portion for supplying a primary current to the primary coil. And a secondary side connector section for taking out a high voltage from the secondary coil to the outside, wherein the iron core, the primary coil, the secondary coil, the primary side connector section, and the secondary side connector section are made of insulating resin. In the ignition coil integrally molded by the above, the conductor for detecting the ignition voltage is provided on the outer peripheral side of the conductor forming the secondary side connector part with a predetermined distance from the surface of the conductor of the secondary side connector part. Is provided, and a detection capacitor for detecting an ignition voltage is formed between the secondary-side connector portion conductor and the ignition voltage detection conductor.

In the proposed structure as described above, the detection conductor constituting the detection capacitor for detecting the ignition voltage for detecting the misfire in the spark ignition type internal combustion engine has a structurally stable ignition. Since it is provided inside the coil resin molded body, the detection conductor is displaced due to mechanical vibration, as in the conventional case where the detection conductor is provided in the high voltage cord of the ignition system, or Since it is not affected by humidity, water, or oil or dust, it is possible to prevent the electrostatic capacitance of the detection capacitor from changing due to these factors, and therefore the ignition voltage is always changed to its waveform. Can be accurately detected up to
The presence or absence of misfire can be accurately determined, and the material of the insulator (dielectric) interposed between the detecting conductor and the conductor inside the secondary side connector is detected by the high voltage cord. It is not limited to rubber that easily deteriorates as in the conventional case in which a conductor for electrical equipment is installed, and it is possible to use resin, which is a molding material for the ignition coil, or even a durable material such as ceramics. It is possible to reliably prevent the occurrence of a situation that causes a failure of the misfire detection device due to the insulation voltage of the detection capacitor being destroyed due to the deterioration of the insulation property, and the ignition voltage leaking. Since it can be embedded together when molding the ignition coil, it does not require extra work to attach the detection conductor, and once the detection conductor is provided, subsequent maintenance is required. Etc. becomes unnecessary, and various effects are obtained.

[0012]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
According to the structure proposed in No. 136249, it is possible to largely eliminate the problem in the case of the conventional structure in which the detecting conductor is provided in the high voltage cord.

By the way, generally, when the ignition voltage is detected by the capacitance probe method, if the capacitance of the detection capacitor is large, the detection voltage becomes large and the detection accuracy becomes high. However, in the structure proposed above, it is practically difficult to sufficiently increase the capacity of the detection capacitor, and therefore, it is not sufficient in terms of improving the detection accuracy of the ignition voltage.

Specifically, the capacitance of the capacitor is determined by the distance between opposing electrodes (counter electrode distance) and the area of the opposing electrodes (counter electrode area). The smaller the counter electrode distance, the more
Also, the larger the counter electrode area, the larger the capacitance of the capacitor, and therefore the higher the detection accuracy. However, in the case of the proposed ignition coil structure, detection conductors are provided on the outer peripheral side of the secondary side connector portion conductor at a predetermined interval, and the outer peripheral surface of the secondary side connector portion conductor and the detection surrounding it. Since the detection capacitor is formed between the detection conductor and the detection conductor, in order to increase the capacitance and increase the detection accuracy, the distance between the detection conductor and the secondary-side connector section conductor must be reduced. It is conceivable that the facing area between the detection conductor and the secondary-side connector portion conductor is increased. However, the distance between the conductor for detection and the conductor for the secondary side connector should be made too small from the viewpoint of corona discharge or leakage current, or the deformation of the conductor for detection due to pressure during injection of mold resin. I can't. Also, the facing area between the detection conductor and the secondary-side connector conductor is determined by the outer diameter of the secondary-side connector conductor, but the outer diameter is restricted by the general-purpose connector and is usually compared. It has to be a relatively small value. Therefore, in the structure proposed above, it is difficult to sufficiently increase the capacity of the detecting capacitor, and therefore, the accuracy of detecting the ignition voltage cannot be sufficiently increased.

Of course, instead of a general-purpose secondary side connector,
It is possible to increase the capacitance of the detection capacitor to some extent by using a connector with a large outer diameter of the conductor part, but in that case, not only will the cost of the connector itself rise, but also the design of other parts. Modifications and shape changes will be required, resulting in a significant cost increase.

Therefore, the inventors of the present invention arranged a plate-shaped electrode plate electrically connected to the output end of the secondary coil inside the case at a position outside the secondary coil in the case of the ignition coil device. , A conductive plate-shaped counter electrode plate is arranged at a predetermined distance from the surface of the electrode plate so as to be parallel to the electrode plate, and the ignition voltage is applied between the electrode plate and the counter electrode plate. We are considering forming a detection capacitor for detection.

In this case, the electrode plate is arranged inside the case of the ignition coil device and outside the secondary coil, that is, in the space between the inner peripheral surface of the case and the outer peripheral surface of the secondary coil. This space is a portion filled with an insulating resin for molding, and is generally a continuous space along the outer periphery of the secondary coil. Therefore, the electrode plate is arranged along the outer periphery of the secondary coil. If arranged in the direction,
The area of the electrode plate can be made sufficiently large. The counter electrode plate facing the electrode plate can also have a large area. Therefore, it is possible to sufficiently increase the area of the electrode plate and the counter electrode plate to sufficiently increase the capacitance of the voltage detecting capacitor and increase the detection voltage, thereby sufficiently increasing the detection accuracy. That is, by increasing the detection voltage level with respect to the noise level and increasing the S / N ratio,
It is possible to improve the detection accuracy.

When the electrode plate is arranged in the space between the inner surface of the case and the outer peripheral surface of the secondary coil in the ignition coil device as described above, it corresponds to the primary coil bobbin or the secondary coil high-voltage side of the secondary coil bobbin. It is electrically desirable to support it at the end and to arrange it so as to extend from the end on the high voltage side in parallel with the outer peripheral surface of the secondary coil.

That is, the electrode plate is electrically connected to the high-voltage side output end of the secondary coil, and is kept at substantially the same potential as the high-voltage side output end of the secondary coil, and therefore the electrode plate and Even if the distance from the high voltage side end of the secondary coil is small, there is no problem because the potential difference between them is small, but the distance between the electrode plate and the low voltage side (close to ground potential) end of the secondary coil is small. If it is small, corona discharge or leakage current may occur between them. Therefore, when arranging the electrode plate on the outer peripheral side of the secondary coil in parallel with the outer peripheral surface of the secondary coil, it should be provided at a position closer to the high voltage side than the low voltage side of the secondary coil. Appropriate.
For that purpose, the structural support of the electrode plate is performed near the high-voltage side end of the secondary coil in the primary coil bobbin or the secondary coil bobbin, and the electrode plate is made parallel to the outer peripheral surface of the secondary coil from the high-voltage side end. It is conceivable that the tip of the electrode plate is extended and kept at a position a certain distance from the end on the low voltage side of the secondary coil. And in this case
The electrode plate is supported in a so-called cantilever state in which the base end is supported near the end on the high voltage side of the secondary coil and the tip is a free end. The counter electrode plate is supported in the state of being fixed to the case side so as to be parallel to the electrode plate supported in the cantilever state as described above.

On the other hand, in assembling the ignition coil device,
After placing each component including the electrode plate and the counter plate in a predetermined position in the case, inject insulating resin such as epoxy resin.
It is usually filled and molded. Therefore, when the electrode plate is supported in a cantilevered state as described above, the electrode plate that is supported in a cantilevered state will be supported by the pressure after the mold resin is injected even if it is set in the correct position before the mold resin is injected. It deforms and its tip (the free end opposite to the structurally supported side) approaches the counter plate abnormally,
In extreme cases, it may come into contact with the counter plate.
In addition, the tip of the electrode plate may approach or come into contact with the counter electrode plate due to a defect in the mounting of the electrode plate or an error in shape and dimension. If the tip of the electrode plate abnormally approaches or contacts the counter electrode plate in this way, corona discharge or leakage current may occur between the electrode plate and the counter electrode plate, causing a signal processing circuit, etc. Adversely affect.

The present invention has been made in view of the above circumstances, and improves the accuracy of misfire determination by providing an electrode plate and a counter electrode plate in the ignition coil device to increase the capacity of the ignition voltage detecting capacitor. At the same time, it is an object of the present invention to provide a structure that prevents abnormal contact and contact of the electrode plate with the counter electrode plate as described above.

[0022]

In order to solve the above-mentioned problems, in the ignition coil device of the present invention, basically, an intermediate position between the cantilever-supported electrode plate and the counter electrode plate parallel to the electrode plate is supported. In addition, a partition wall made of a hard insulating material is interposed.

Specifically, the invention of claim 1 is an iron core,
An ignition coil having a primary coil and a secondary coil wound around the iron core, the primary coil and the secondary coil being housed in a case made of hard resin and integrally molded with an insulating resin. In the device, an electrode plate electrically connected to the output end of the secondary coil is fixed at a position on the outer peripheral side of the secondary coil in the case, and a base end portion is fixed near the high voltage side end portion of the secondary coil. And a counter electrode plate is disposed in the case at a predetermined interval with respect to the electrode plate so as to be parallel to the electrode plate, and an intermediate position between the electrode plate and the counter electrode plate. Is provided with a partition wall made of a hard insulating material, and a capacitor for detecting an ignition voltage is formed between the electrode plate and the counter electrode plate.

According to a second aspect of the invention, in the ignition coil device according to the first aspect of the invention, the partition wall portion is integrally and continuously projected from the inner surface of the case.

Furthermore, the invention of claim 3 is the ignition coil device of the invention of claim 1, characterized in that the tip portion of the electrode plate is engaged with the tip portion of the partition wall portion.

[0026]

In the ignition coil device of the present invention, the electrode plate disposed at a position outside the secondary coil in the case of the ignition coil device and a predetermined electrode plate so as to be parallel to the electrode plate. And a counter electrode arranged at a distance from each other form a capacitor for detecting an ignition voltage, that is, a capacitance probe as an ignition voltage detecting means for detecting an ignition voltage for detecting misfire. If a high voltage for spark discharge in the spark plug is induced in the secondary coil of the ignition coil, the electrostatic capacitance between the electrode plate conducted to the output end of the secondary coil and the counter electrode plate facing it. Induces a high voltage on the return plate. Therefore, by extracting the voltage as a detection voltage by capacitance division, etc., performing appropriate signal processing, and comparing it with a reference signal (usually a signal corresponding to the normal detection voltage waveform during non-misfire), the misfire state Can be determined.

Here, the electrode plate is continuous inside the case of the ignition coil device and outside the secondary coil, that is, along the outer circumference of the secondary coil between the inner circumference of the case and the outer circumference of the secondary coil. Is disposed in a space (a portion filled with an insulating resin for molding), and therefore, as described above, the area of the electrode plate can be sufficiently increased, and the electrode plate faces the electrode plate. The counter electrode can also have a large area. Therefore, it is possible to sufficiently increase the area of the electrode plate and the counter electrode plate to sufficiently increase the capacitance of the voltage detecting capacitor and increase the detection voltage, thereby sufficiently increasing the detection accuracy. That is, the detection voltage level is increased with respect to the noise level, and S
The detection accuracy can be increased by increasing the / N ratio.

The tip of the electrode plate is fixed near the high voltage side end of the secondary coil and is in a so-called cantilevered support state. Hard insulation is provided at an intermediate position between the electrode plate and the counter electrode plate. Since the partition wall made of material is interposed, the tip of the electrode plate becomes the counter electrode plate due to deformation of the electrode plate due to the injection pressure when molding resin is injected into the case, or electrode plate mounting failure or shape error. It is possible to prevent abnormal approach and contact by the partition wall portion.

In the ignition coil device according to the second aspect of the present invention, the partition wall portion is integrally and continuously projected from the inner surface of the case, so that the partition wall portion can be integrally formed when the case is molded.

Further, in the case of the ignition coil device according to the third aspect of the present invention, not only is the partition wall similar to the above interposed between the electrode plate and the counter electrode plate, but the tip of the electrode plate is located at the tip of the partition. Since they are engaged and their positions are fixed, it is possible to more reliably prevent the tip of the electrode plate from approaching or contacting the counter electrode abnormally.

[0031]

1 to 3 show an ignition coil device according to a first embodiment of the present invention. In this first embodiment, an ignition coil device is provided in a one-to-one correspondence with the ignition plug of each cylinder of the engine, and the secondary voltage of the ignition coil device is directly supplied to the ignition plug without passing through a distributor. I chose
As an example of an ignition coil device applied to an ignition system called a DLI type (distributorless ignition type) or a DI type (direct ignition type), an embodiment in which an ignition coil device is integrally connected to an ignition plug cap will be shown. .

1 to 3, an ignition coil device 3 is attached to an upper end of an ignition plug cap 2 which covers the ignition plug 1. In this ignition coil device 3, a primary coil 6 is wound around one side of an iron core 4 having a rectangular shape as a whole via a primary coil bobbin 5 having a rectangular cross section made of synthetic resin, and further on the outer periphery of the primary coil 6. The secondary coil 8 is wound by split winding via a secondary coil bobbin 7 having a rectangular cross section. The primary coil 6 and the secondary coil 8 are entirely housed in a case 9 made of a hard resin such as PBT (polybutyl terephthalate), and are insulated from an epoxy resin or the like injected / filled into the case 9. It is integrally molded with the resin. The portion of the case 9 surrounding the secondary coil 8 is formed so as to have a rectangular parallelepiped shape substantially along the outer diameter contour of the secondary coil 8. Further, a hollow cylindrical connecting cylinder 11 protruding downward is integrally formed on the lower surface of the case 9, and a conductive shaft 12 made of a good conductive material such as copper is provided in the connecting cylinder 11. ing. The upper end of the conductive shaft 12 projects into the case 9, and the output end 8A of the secondary coil 8 is connected to the projecting portion via a diode 27 for suppressing a reverse current and a conductive member 16. A connector 17 for supplying a primary current to the primary coil 6 is provided on the side of the case 9.

Further, the electrode plate 13 is provided on the upper part of the case 9.
And the counter electrode plate 14 is disposed. These electrode plates 1
3 and the counter electrode plate 14 constitute a capacitor 15 for detecting an ignition voltage, as will be described later.
Both are made of a thin plate made of a highly conductive material such as copper.

As shown in FIGS. 2 and 3, the electrode plate 13 is formed so as to have an inverted L-shaped cross section as a whole, and its base end portion 13A is on the high voltage side of the secondary coil 8 in the primary coil bobbin 5. It is fixed at a position close to the end portion 8B via a support base 18 made of an insulating material, and its base end portion 13A.
From the vicinity of the high-voltage side end 8B of the secondary coil 8 toward the low-voltage side end 8C along the outer peripheral surface of the secondary coil 8, and the flat-plate part 13B is bent. It constitutes the electrode part. However, the tip portion of the electrode plate 13 (tip portion of the flat plate portion 13B) 13C is separated from the low-voltage side end portion 8C of the secondary coil 8 by a certain distance D. The electrode plate 13 is electrically connected to the output end 8A 'of the secondary coil 8 via the conductive member 19 at the portion on the base end 13A side.

On the other hand, the counter electrode plate 14 is the flat plate portion 1 of the electrode plate 13.
It is arranged near the inner peripheral surface of the upper part of the case 9 so as to be parallel to 3B. The counter electrode plate 14 is formed as a flat plate as a whole, and both edges thereof are engaged with the mounting grooves 9A formed in the inner corner of the case 9 to fix the position. The counter electrode plate 14 is electrically guided to the connector portion 17 via the conductive member 20.

Further, a partition wall portion 21 is interposed between the electrode plate 13 and the counter electrode plate 14 described above. This partition 21
Is integrally and continuously projected from the inner surface on the side wall side of the case 9 so as to be parallel to the electrode plate 13 and the counter electrode plate 14, and is therefore made of a PBT-based hard resin like the case 9. An insulating resin (mold resin) 10 such as an epoxy resin filled in the case 9 is interposed between the electrode plate 13, the partition wall portion 21, and the counter electrode plate 14 after the ignition coil device is assembled. Therefore, the electrode plate 13 and the counter electrode plate 14 constitute a capacitor 15 for detecting the ignition voltage, which uses the mold resin 10 and the hard resin of the partition wall portion 21 as a dielectric.

The ignition coil device 3 as described above is coupled to the upper end portion of the ignition plug cap 2, but the ignition plug cap 2 itself has a conventional ignition coil used in a DLI type ignition system. It may have the same structure as the integrally coupled spark plug cap. That is, the spark plug cap 2 has a hollow cylindrical shape as a whole.
An upper insertion chamber 22 into which the connecting cylinder 11 of the ignition coil device 1 is inserted is an upper portion of a hollow portion formed integrally with a hard resin such as BT and along the axial direction of the ignition plug cap 2. It is said that. At the center of the hollow portion of the spark plug cap 2, the conductive spring 2 is attached to the lower end of the conductive shaft 12 in the ignition coil device.
A shaft-bar-shaped conductor 24 that electrically and mechanically contacts via 3
Is inserted along the axial direction, and the terminal portion 1A above the spark plug 1 is provided in the lower portion of the hollow portion.
A cap chamber 25 is formed to cover and be fixed to
Inside the cap chamber 25, there is provided a connector portion 26 that is electrically connected to the conductor 24 and is in electrical contact with the terminal portion 1A of the spark plug 1.

In the ignition coil device 3 of the above-described ignition plug cap integrated type, if the current of the primary coil 6 is interrupted by a signal from an ignition timing control means (not shown), a high voltage is generated in the secondary coil 8. To do. This high voltage is applied to the conductive shaft 12 from the output terminal 8A of the secondary coil 8 through the diode 27 for suppressing the reverse current and the conductive member 16, and further, from the conductive shaft 12 to the spark plug cap 2.
The spark plug 1 reaches the spark plug 1 through the conductive spring 23, the conductor 24, and the connector portion 26, and spark discharge is generated between the electrodes of the spark plug 1. At this time, a voltage is induced in the detection capacitor 15 constituted by the flat plate portion 13B of the electrode plate 13 and the counter electrode plate 14 in the ignition coil device 3, and this voltage is taken out by electrostatic partial pressure or the like to obtain a detection voltage. The presence or absence of misfire is detected by being applied to a misfire detection device (not shown) and comparing the waveform of the detected voltage with that of a reference.

Here, the capacitor 15 for detecting the ignition voltage
Is composed of a flat plate portion 13B of the electrode plate 13 arranged in a space outside the secondary coil 8 in the case 9 and a counter electrode plate 14 provided in parallel with the flat plate portion 13B. 8 is sufficiently wide in a direction along the outer surface of the electrode 8 and the inner surface of the case 9, the flat plate portion 1 of the electrode plate 13
The areas of 3B and the counter electrode plate 14 can be made sufficiently large, so that the counter electrode area as the capacitor 15 can be made sufficiently large to increase the capacitance thereof. Therefore, the detection voltage of the ignition voltage can be increased to sufficiently increase the detection accuracy of the ignition voltage and thus the accuracy of misfire detection. The tip of the tip 13C of the electrode plate 13 and the tip 8C of the secondary coil 8 on the low-voltage side are separated by a considerable distance D, and therefore corona discharge or leakage current may occur between them. Few.

Further, a partition wall portion 21 is interposed between the flat plate portion 13B of the electrode plate 13 and the counter electrode plate 14, and this partition wall portion 21 is integrally formed with the case 9 by the hard resin, that is, It is present before injection of the molding resin 10. Therefore, even when the electrode plate 13 is deformed by the injection pressure when the mold resin 10 is injected, the partition wall portion 21 blocks the electrode plate 13 and the electrode plate 13 is blocked.
It is prevented that the tip portion 13C of the above-mentioned approaches the counter electrode plate 14 to a certain extent or more, and of course it is prevented from coming into contact with the counter electrode plate 14. In addition, it is possible to effectively prevent the tip portion 13C of the electrode plate 13 from abnormally approaching or coming into contact with the counter electrode plate 14 due to a mounting defect of the electrode plate 13 or a shape error.

4 and 5 show a second embodiment of the present invention. This second embodiment also shows an example applied to the ignition coil device of the spark plug cap integral coupling type used in the DLI type ignition system. 4 and 5, elements common to those of the first embodiment shown in FIGS. 1 to 3 are designated by the same reference numerals, and the description thereof will be omitted.

In FIGS. 4 and 5, the tip portion 21A of the partition wall portion 21 slightly projects toward the secondary coil 8, and an engaging groove 21B is formed in this projecting portion 21A. The tip portion 13 of the electrode plate 13 is formed in the groove 21B.
C is engaged.

In the embodiment shown in FIGS. 4 and 5, since the tip portion 13C of the electrode plate 13 is engaged and fixed to the tip portion 21A of the partition wall portion 21, when the mold resin is injected as described above. Tip portion 1 of the electrode plate 13 due to deformation or mounting failure due to the injection pressure of the
It is possible to more reliably prevent the 3C from abnormally approaching the counter electrode plate 14.

In each of the above embodiments, the electrode plate 1
3 and the counter electrode plate 14 are provided on the upper portion of the case 9 (a portion opposite to the conductive shaft 12), but may be provided on a lateral portion of the case 9 in some cases. Of course, in that case, the partition wall portion 21 is also formed integrally with the case 9 in a lateral portion of the case 9. Further, it is advantageous in manufacturing that the partition wall portion 21 is integrally formed with the case 9 as shown in each of the above-described embodiments, but it may be provided separately from the case 9 in some cases. As the hard insulating material forming the partition wall portion 21, hard rubber, ceramics or the like can be used in addition to the hard resin.

Although each of the above embodiments has been shown as an example applied to an ignition coil device of a spark plug cap integral coupling type used in a DLI type ignition system, the present invention is used in an ignition system having a distributor. The present invention can also be applied to an ignition coil device of the type described above, that is, an ignition coil device of a type in which the ignition plug cap is not integrally connected.

[0046]

According to the ignition coil device of the present invention,
The electrode plate electrically connected to the output end of the secondary coil is placed inside the case and on the outer circumference side of the secondary coil with the base end fixed near the high-voltage side end of the secondary coil. Was set up,
In addition, a counter electrode plate is arranged so as to be parallel to the electrode plate, and a detection capacitor for detecting an ignition voltage is formed between the electrode plate and the counter electrode plate. Since it is possible to make a sufficiently large area along the outer peripheral surface of the next coil, and the counter electrode plate can be made to have a sufficiently large area correspondingly, the counter electrode area of the detecting capacitor can be made large and By increasing the electric capacity, the accuracy of detection of the ignition voltage can be sufficiently improved, and the accuracy of misfire determination can be improved. And since the partition wall portion made of a hard insulating material is interposed at an intermediate position between the electrode plate and the counter electrode plate which form the capacitor for detecting the ignition voltage,
It is effective for the tip of the electrode plate to approach or come into contact with the counter electrode abnormally due to deformation of the electrode plate due to pressure when injecting mold resin into the case, or mounting plate electrode defect or shape error. Therefore, it is possible to prevent corona discharge and leakage current from occurring due to abnormal approach or contact of the electrode plate tip to the counter electrode plate, and therefore adversely affect the signal processing circuit etc. due to these. Can be effectively prevented. Further, the electrode plate is arranged in the space inside the case of the ignition coil device, and the counter electrode plate only needs to be provided in parallel with the electrode plate. There is no companion.

The ignition coil device according to the invention of claim 2 is
Since the partition wall portion interposed between the electrode plate and the counter electrode plate is formed integrally with the case, the partition wall portion can be formed at the same time as the case is molded, and therefore, the cost increase required for forming the partition wall portion is small. I'm done.

Further, in the ignition coil device of the third aspect, since the tip of the electrode plate is engaged with the tip of the partition wall and the position thereof is fixed, the tip of the electrode plate abnormally approaches the counter electrode plate. More reliably to prevent or contact
It is possible to reliably prevent generation of corona discharge and leakage current between the electrode plate and the counter electrode plate.

[Brief description of drawings]

FIG. 1 shows an ignition coil device according to a first embodiment of the present invention,
It is a vertical front view shown with an ignition plug cap and an ignition plug.

FIG. 2 is a vertical sectional front view showing an enlarged main part of the embodiment of FIG.

FIG. 3 is a vertical cross-sectional side view showing an enlarged main part of the embodiment of FIG.

FIG. 4 is an enlarged vertical sectional front view showing an ignition coil device according to a second embodiment of the present invention.

5 is an enlarged vertical side view of the embodiment of FIG.

FIG. 6 is a schematic diagram showing a voltage detecting means in a conventional misfire detecting device.

[Explanation of symbols]

 1 Ignition plug cap 2 Ignition plug 3 Ignition coil device 4 Iron core 6 Primary coil 8 Secondary coil 9 Case 10 Mold resin 13 Electrode plate 14 Counter electrode plate 15 Detection capacitor 21 Partition wall

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Hisaki Inside the Honda R & D Co., Ltd. 1-4-1, Chuo, Wako, Saitama

Claims (3)

[Claims] 1. An iron core, and a primary coil and a secondary coil wound around the iron core, wherein the primary coil and the secondary coil are housed in a case made of hard resin and are made of an insulating resin. In the ignition coil device integrally molded by, in the position on the outer peripheral side of the secondary coil in the case,
An electrode plate electrically connected to the output end of the secondary coil is arranged with the base end fixed near the high voltage side end of the secondary coil, and the electrode plate is provided in the case. A counter electrode plate is arranged at a predetermined distance from the electrode plate so as to be parallel to the electrode plate, and a partition wall made of a hard insulating material is provided at an intermediate position between the electrode plate and the counter electrode plate. An ignition coil device characterized in that a capacitor for detecting an ignition voltage is formed between the plate and the counter electrode plate. 2. The ignition coil device according to claim 1, wherein the partition wall portion is configured to continuously and integrally project from an inner surface of the case. 3. The ignition coil device according to claim 1, wherein a tip portion of the electrode plate is engaged with a tip portion of the partition wall portion.