JP3097229U - Ignition device and coil device - Google Patents

Abstract

An igniter capable of ensuring a sufficient arc discharge maintenance time even when a primary coil or a secondary coil is downsized, and a technique related thereto.
In an ignition device, when a current in a primary coil is interrupted by a switching element, a high voltage is induced in a secondary coil, and the high voltage is supplied to an ignition plug. At this time, a series resonance circuit including the tertiary coil L3 and the capacitor C1 equivalently formed in the space between the open end and the terminal connection end of the tertiary coil L3 resonates due to the magnetic flux change in the secondary coil L2. A large induced current is generated in the tertiary coil L3. Then, due to the large magnetic flux change generated in the tertiary coil L3 due to the generation of the induced current, a high voltage is induced again in the secondary coil L2, and this high voltage is supplied to the ignition plug.
[Selection diagram] FIG.

Description

[0001]
[Technical field to which the invention belongs]
The present invention relates to an ignition device for generating an arc discharge in a spark plug, and a related technique.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, an ignition device for generating an arc discharge in a spark plug attached to a cylinder of an engine of a vehicle or the like generally includes a primary coil and a secondary coil, which are inductively coupled to each other. By interrupting the current flowing through the primary coil, a high voltage is induced in the secondary coil, and this high voltage is supplied to the ignition plug to provide a space (discharge gap) between the discharge electrode and the ground electrode in the ignition plug. An arc discharge is generated. The arc discharge generates a flame nucleus (that is, a kind of fire) for burning the air-fuel mixture in a cylinder of the engine, and the air-fuel mixture is burned as the flame nucleus sequentially expands and grows.
[0003]
Here, the configuration of such an ignition device is general as described above, and corresponds to a publicly-known / public technology. Therefore, here, the prior art document is not particularly disclosed.
[0004]
[Problems to be solved by the invention]
Incidentally, in recent years, ignition devices have been downsized, and accordingly, the peak value of high voltage generated in the secondary coil has been reduced. For this reason, when the density of the air-fuel mixture is large and the electric resistance in the discharge gap is large, the arc discharge may not be able to be maintained until the flame kernel has grown sufficiently. As a result, there is a problem that the air-fuel mixture cannot be sufficiently burned, and the output of the engine is correspondingly lost, and many harmful substances or unburned substances are generated.
[0005]
In order to solve the above problems, the present invention provides an igniter capable of ensuring a sufficient arc discharge maintenance time even if the primary coil and the secondary coil are downsized, and a technique related thereto. The purpose is to provide.
[0006]
[Means for Solving the Problems and Effects of the Invention]
In order to achieve the above object, the invention according to claim 1 includes a first coil and a second coil which are inductively coupled to each other, and intermittently interrupts a current flowing through the first coil. An ignition device for inducing a high voltage in a coil and generating an arc discharge in an ignition plug by the high voltage, wherein the ignition device is inductively coupled to a second coil, one end is opened, and the other end is an induction current. And a third coil connected to an outflow path for outflow.
[0007]
In the ignition device configured as described above, the space between the open end of the third coil and the other end connected to the outflow path (however, a space that does not pass through the third coil itself) is equivalent. And a third coil forms a series resonance circuit with the capacitor. Therefore, if the number of turns of the third coil is adjusted so that the series resonance circuit resonates when a high voltage is induced in the second coil and the magnetic flux of the second coil changes, Every time a high voltage is induced in the second coil, the series resonance circuit resonates, and a large induced current is generated in the third coil. Since a large voltage change is induced in the second coil again due to a large change in magnetic flux generated in the third coil due to the generation of the induced current, the arc discharge of the ignition plug can be maintained for that long.
[0008]
That is, according to the present invention, it is possible to provide an ignition device that can secure a sufficient arc discharge maintenance time even if the primary coil and the secondary coil are downsized.
Here, it is desirable that the above-mentioned outflow path is, for example, a reference point of a potential in the first coil and the second coil.
[0009]
That is, since the potential of the third coil is the same as the potential reference point of the first and second coils, the series resonance circuit is in a stable resonance state.
The first, second, and third coils may be arranged in parallel with each other, but in consideration of the efficiency of converting a change in magnetic flux into electric power, the first, second, and third coils are arranged concentrically. It is desirable to have been.
[0010]
The third coil may be built in the ignition device, for example, as described in claim 4. In the case where the second coil is encased in an outer wall through which magnetic flux can pass, For example, an exterior may be provided around the outer wall.
[0011]
When the third coil is provided around the outer wall, the third coil may be detachably attached to the outer wall.
Here, any of the above-described ignition devices can be suitably used, for example, as a direct ignition type ignition device as described in claim 7, and can be mounted on a vehicle, for example, as described in claim 8. It can be suitably used as an ignition device to be used.
[0012]
According to a ninth aspect of the present invention, a conductor wire is wound around an outer peripheral wall of a cylindrical core portion through which an ignition device can be inserted, one end of the conductor wire is opened, and a connection terminal is connected to the other end. It is a coil device.
That is, since the coil device thus configured can be attached to and detached from the ignition device, it can be suitably used as the third coil in the ignition device according to the sixth aspect.
[0013]
In this coil device, it is desirable that the outer peripheral wall of the core except for the connection terminal be molded with an insulator together with the conductor wire.
With this configuration of the coil device, it is possible to prevent the conductor wire of the coil device from being short-circuited to the internal combustion engine when the ignition device is mounted on the internal combustion engine, thereby preventing the characteristics of the series resonance circuit from fluctuating.
[0014]
Further, the insulator is a dielectric of the capacitor equivalently formed in a space between the open end of the conductor wire and the other end to which the connection terminal is connected (a space not passing through the conductor wire itself). Since the capacitance and the capacity of the capacitor can be increased, the sharpness of the series resonance circuit formed by the coil device and the capacitor can be reduced. That is, the series resonance circuit can resonate even if the cycle at which arc discharge is generated in the spark plug varies (that is, the rotational speed of the internal combustion engine varies).
[0015]
[Embodiment of the invention]
An embodiment of the present invention will be described below with reference to the drawings.
First, FIG. 1 is a structural diagram of an ignition device 1 according to the present invention. However, FIG. 1 is a schematic diagram showing only the portion according to the present invention.
[0016]
As shown in FIG. 1, the ignition device 1 includes a cylindrical main body 3 and a coil device 5 mounted on an outer peripheral wall of the main body 3, and is configured to be mountable on a cylinder head of a vehicle engine. ing.
Here, the main body 3 is provided with a center core 9 made of an iron core, a primary coil L1, and a secondary coil L2 inside the center of a cylindrical case 7, and the ignition device 1 is provided with a distributor and a high tension cord ( It is configured as a so-called direct ignition system that does not require high-voltage wiring.
[0017]
The case 7 is made of a resin that can withstand heat generated in the internal combustion engine and can transmit magnetic flux. The center core 9, the primary coil L1, and the secondary coil L2 are arranged concentrically and inductively coupled to each other, while an insulating bobbin (not shown) is interposed therebetween. It is electrically insulated. However, the number of turns of each of the primary coil L1 and the secondary coil L2 is set so that a high voltage (10000 V to 20,000 V) is generated in the secondary coil L2 when the current flowing through the primary coil L1 is momentarily interrupted. ing.
[0018]
A storage space 11 for storing an electrode portion of a spark plug (not shown) is formed at a lower end of the case 7. A metal joint 13 electrically connected to one end of the secondary coil L2 is provided at an upper end of the storage space 11, and the joint 13 has a metal joint for receiving an electrode of a spark plug. A spring 15 is attached to the storage space 11 so as to project therefrom. That is, one end of the secondary coil L2 is connected to the electrode of the ignition plug via the joint 13 and the spring 15.
[0019]
A connector connection portion 17 for connecting a connector (not shown) is formed at the upper end of the case 7. The connector connection portion 17 includes a connection terminal 19 connected to one end of the primary coil L1, a connection terminal 21 connected to the other end of the primary coil L1, and a connection end of the secondary coil L2 to the ignition plug. Is provided with a connection terminal 23 connected to the other end on the opposite side, and a connection terminal 25 connected to the ground electrode of the ignition plug. However, the connection terminals 19 and 21 are connected to a battery (see FIG. 3) mounted on the vehicle and a switching element (see FIG. 3) for interrupting the current flowing through the primary coil L1 via connectors. The connection terminals 23 and 25 are both connected to a vehicle body via a connector (so-called body earth).
[0020]
Next, FIG. 2 is a structural diagram of the coil device 5.
As shown in FIG. 2, the coil device 5 includes a cylindrical core 51 made of the same resin as the case 7 of the ignition device 1, and an enamel wire is wound around an outer peripheral wall of the core 51. , And a tertiary coil L3. However, one end of the tertiary coil L3 is open, and a crimp terminal 55 is connected to the other end via a copper wire 53 covered with an insulator.
[0021]
In the coil device 5, except for the copper wire 53 and the crimp terminal 55, the outer peripheral wall of the core 51 is molded with a resin 57 that can transmit magnetic flux together with the tertiary coil L3.
The coil device 5 is mounted on the outer peripheral wall of the main body 3 by inserting the main body 3 through the core 51. When the coil device 5 is mounted on the cylinder head together with the main body 3, the crimp terminal 55 is connected to the cylinder of the engine. Fastened to the head by bolts.
[0022]
Here, FIG. 3 is a circuit diagram of an electric circuit formed between the ignition device 1 and the vehicle.
As shown in FIG. 3, the primary coil L1 has one end connected to the battery B1 and the other end connected to a vehicle body via a switching element (for example, a transistor) Tr1. The secondary coil L2 has one end connected to the vehicle body and the other end connected to a spark plug (not shown).
[0023]
One end of the tertiary coil L3 connected to the crimp terminal 55 (hereinafter, referred to as “terminal connection end”) is connected to a cylinder head (vehicle body). Here, a capacitor C1 is equivalently formed in the space between the open end of the tertiary coil L3 and the terminal connection end (however, a space that does not pass through the tertiary coil L3 itself). Together with a series resonance circuit. However, the number of turns of the tertiary coil L3 is adjusted so that the series resonance circuit resonates when a high voltage is induced in the secondary coil L2 and the magnetic flux of the secondary coil L2 changes.
[0024]
In the ignition device 1 configured as described above, when the current in the primary coil L1 is interrupted by the switching element Tr1, a high voltage is induced in the secondary coil L2, and this high voltage is supplied to the ignition plug. At this time, the series resonance circuit including the tertiary coil L3 and the capacitor C1 resonates due to a change in magnetic flux in the secondary coil L2, and a large induced current is generated in the tertiary coil L3. Then, due to the large magnetic flux change generated in the tertiary coil L3 due to the generation of the induced current, a high voltage is induced again in the secondary coil L2, and this high voltage is supplied to the ignition plug.
[0025]
That is, in the ignition device 1 of the present embodiment, every time a high voltage is induced in the secondary coil L2, a large induced current is generated in the tertiary coil L3 due to resonance, and as a result, the high voltage is again applied to the secondary coil L2. , The arc discharge of the spark plug can be maintained for that long.
[0026]
That is, according to the igniter 1 of the present embodiment, it is possible to provide an igniter capable of ensuring a sufficient arc discharge maintenance time even if the primary coil and the secondary coil are downsized.
Further, in the ignition device 1 of the present embodiment, one end of the tertiary coil L3 in the coil device 5 is body-grounded together with the primary coil L1 and the secondary coil L2, so that the series resonance circuit is in a stable resonance state.
[0027]
Further, since the outer peripheral wall of the coil device 5 is covered with the resin 57, when the ignition device 1 is mounted on the cylinder head, the tertiary coil L3 is short-circuited to the engine, and the characteristics of the series resonance circuit fluctuate. There is no.
Further, since the resin 57 covering the outer peripheral wall of the coil device 5 acts as a dielectric of the capacitor C1 and increases the capacitance of the capacitor C1, the sharpness of the series resonance circuit formed by the tertiary coil L3 and the capacitor C1 is increased. The degree can be reduced. That is, even if the cycle at which arc discharge is generated in the spark plug varies (that is, the engine speed varies), the series resonance circuit can resonate.
[0028]
As described above, the embodiments of the present invention have been described. However, the present invention is not limited to the above embodiments, and it goes without saying that various forms can be adopted as long as they belong to the technical scope of the present invention. .
For example, in the above-described embodiment, the tertiary coil L3 is provided on the ignition device 1, but may be incorporated in the ignition device 1 so as to be concentrically arranged outside the secondary coil L2. This case is suitable when the case 7 of the ignition device 1 is made of a material that does not transmit magnetic flux, such as a metal.
[0029]
In the above embodiment, the present invention is applied to an ignition device of a direct ignition system. However, any other ignition device that generates a high voltage using a primary coil and a secondary coil and supplies it to an ignition plug can be used. The present invention may be applied to an ignition system of a system.
In the above embodiment, the capacitor C1 equivalently formed in the space between the open end and the terminal connection end of the tertiary coil L3 is used as a component of the series resonance circuit. They may be connected in parallel, and this may be used as a component of the series resonance circuit.
[Brief description of the drawings]
FIG. 1 is a structural view of an ignition device 1 according to the present invention.
FIG. 2 is a structural view of a coil device 5.
FIG. 3 is a circuit diagram of an electric circuit formed between the ignition device 1 and a vehicle.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Ignition device, 3 ... Main body part, 5 ... Coil device, 7 ... Case, 9 ... Center core, 11 ... Storage space, 13 ... Joint, 15 ... Spring, 17 ... Connector connection part, 19, 21, 23, 25 ... Connection terminal, 51 core, 53 copper wire, 55 crimp terminal, 57 resin, B1 battery, C1 capacitor, L1 primary coil, L2 secondary coil, L3 tertiary coil, Tr1 switching element .

Claims (10)

A first coil and a second coil that are inductively coupled to each other; a current flowing through the first coil is interrupted to induce a high voltage in the second coil; An ignition device for generating an arc discharge,
An ignition device comprising: a third coil that is inductively coupled to the second coil and that has one end open and the other end connected to an outflow path through which an induced current flows. The ignition device according to claim 1, wherein the outflow path is a reference point of a potential in the first coil and the second coil. The ignition device according to claim 1 or 2, wherein the first, second, and third coils are arranged concentrically. The ignition device according to any one of claims 1 to 3, wherein the third coil is built in the ignition device. The second coil is encased on an outer wall that can transmit a magnetic flux,
The ignition device according to any one of claims 1 to 3, wherein the third coil is provided around the outer wall. The ignition device according to claim 5, wherein the third coil is configured to be detachable from the outer wall. The ignition device according to any one of claims 1 to 6, wherein the ignition device is of a direct ignition type. The ignition device according to claim 1, wherein the ignition device is mounted on a vehicle. A coil device comprising: a conductor wire wound around an outer peripheral wall of a cylindrical core portion through which an ignition device can be inserted, one end of the conductor wire being opened, and a connection terminal connected to the other end. The coil device according to claim 9, wherein an outer peripheral wall of the core except for the connection terminal is molded with an insulator together with the conductor wire.

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