JP6503949B2 - Ignition coil and ignition device for internal combustion engine - Google Patents

Description

  The present invention relates to an ignition coil and an ignition device for an internal combustion engine.

  Conventionally, an ignition coil for applying a high voltage to a spark plug to generate a spark discharge is known. Some ignition coils have a primary coil and a secondary coil magnetically coupled to each other. Patent Document 1 discloses that a resistor is disposed between the secondary coil and the spark plug in order to suppress the flow of high frequency noise current into the ignition coil due to the occurrence of spark discharge. It is done.

JP, 2012-251519, A

However, the above-described ignition coil has the following problems.
In recent years, with the demand for higher output of the ignition coil, reduction of the resistance value of the resistor is required. However, if the resistance value of the resistor is simply reduced, the suppression effect of the noise current generated due to the spark discharge is reduced.

  The present invention has been made in view of the above background, and an object of the present invention is to provide an ignition coil and an ignition device for an internal combustion engine capable of suppressing noise current and achieving high output.

One aspect of the present invention is a coil body having a primary coil and a secondary coil,
A cylindrical high-pressure tower projecting from the coil body toward the tip end;
A tubular joint connected to the high pressure tower and extending to the tip end;
A first winding resistor disposed in the high voltage tower and electrically connected to the secondary coil;
A second winding resistor disposed in the joint portion and electrically connected to the first winding resistor;
The second winding resistor comprises a coil spring which can be elastically extended and contracted in the axial direction.
The coil spring includes a closely wound portion in which the windings are in axial contact with each other through an insulating film, a tip elastic portion which is disposed on the tip end side of the closely wound portion and is elastically compressible in the axial direction; A proximal end elastic portion which is disposed on the proximal end side of the portion and which is elastically compressible in the axial direction;
The closely wound portion is an ignition coil for an internal combustion engine characterized in that it has a length of half or more of the total length of the coil spring in the axial direction.

Another aspect of the present invention is an igniter having an ignition coil for the internal combustion engine and a spark plug connected to the ignition coil, wherein
The spark plug has a cylindrical housing, a cylindrical insulator held inside the housing, and a proximal end projecting while exposing a part of the proximal end to the proximal side of the housing. A terminal fitting held inside the insulator, a plug resistor disposed on the tip end side of the terminal fitting and disposed on the inside of the insulator, a tip end side of the plug resistor, A center electrode held inside the insulator so that the tip projects, and a ground electrode forming a spark discharge gap between the center electrode and the center electrode;
The terminal fitting is electrically connected to the coil spring,
A combined electric resistance value of the electric resistance value of the first winding resistor and the electric resistance value of the plug resistor is 1 to 3 kΩ, in an ignition device for an internal combustion engine.

  The ignition coil for the internal combustion engine has a first winding resistor and a second winding resistor connected in series. Therefore, it is easy to increase the inductance in the connection path formed by the first winding resistor and the second winding resistor between the spark plug connected to the ignition coil and the coil body. Furthermore, the second winding resistor is constituted by a close winding portion for half or more of its entire length. Therefore, the inductance of the second winding resistor can be increased. As a result, the inductance of the connection path can be increased. Thus, the ignition coil can obtain high impedance to high frequency noise current in the connection path. On the other hand, since the frequency of the supply current supplied from the ignition coil to the spark plug is sufficiently small, the impedance for the supply current does not increase even if the inductance in the connection path is large. As described above, since the impedance of the connection path with respect to the noise current can be increased by the inductance component, the electric resistance component can be sufficiently reduced. Therefore, in the above-mentioned ignition coil, it is possible to secure noise immunity (noise suppression performance) against noise current while realizing high output.

  In the closely wound portion of the coil spring, the windings are in axial contact with each other via the insulating film. Therefore, it is possible to prevent the windings from shorting in the axial direction. Therefore, while being able to prevent the change of the inductance by short circuiting of windings, it is easy to wind a winding closely in a close-winding part, and it is easy to secure the inductance of the 2nd winding resistor (coil spring).

  Further, Joule heat can also be suppressed by sufficiently reducing the electrical resistance component of the impedance as described above. Therefore, the deterioration of the ignition coil due to heat can be suppressed, and the product life can be improved.

  Also, the second winding resistor comprises a coil spring. Therefore, in addition to the role of causing the second winding resistor to have an inductance, it is also possible to have a role of stably electrically connecting the coil body and the spark plug connected to the ignition coil. Therefore, the number of parts of the ignition coil can be suppressed.

  In the igniter for the internal combustion engine, a combined electric resistance value of the electric resistance value of the first winding resistor and the electric resistance value of the plug resistor is 1 to 3 kΩ. That is, by attaching the spark plug to the ignition coil capable of suppressing the noise current, the combined electrical resistance value of the first winding resistor and the plug resistor can be sufficiently reduced. Thereby, the output of the ignition coil can be further increased. Furthermore, since Joule heat can be suppressed, deterioration of the ignition coil and the spark plug due to heat can be suppressed, and the product life can be improved.

  In addition, the electrical resistance value of the plug resistor of the spark plug is 1 kΩ or more. Therefore, it is possible to prevent the current flowing to the center electrode and the ground electrode of the spark plug from becoming too large, and to reduce the amount of electrode consumption of the center electrode and the ground electrode.

  As described above, according to the above aspect, it is possible to provide an ignition coil and an ignition device for an internal combustion engine that can suppress noise current and can achieve high output.

1 is a cross-sectional view of an ignition coil for an internal combustion engine in Embodiment 1. FIG. FIG. 7 is a front view of the first winding resistor in the first embodiment. FIG. 7 is a front view of a second winding resistor in the first embodiment. FIG. 2 is an enlarged front view of a closely wound portion in Embodiment 1; FIG. 2 is an enlarged cross-sectional view of a coil spring in the first embodiment. FIG. 13 is a front view of a second winding resistor in the second embodiment. FIG. 13 is an enlarged cross-sectional view of the second embodiment of the present invention, showing the vicinity of the closely wound portion and passing through the central axis of the second winding resistor. FIG. 18 is a diagram for illustrating the relationship between the current frequency and the impedance of the first winding resistor and the second winding resistor in the third embodiment. Sectional drawing of the ignition device for internal combustion engines in Embodiment 4. FIG. FIG. 14 is a cross-sectional view of the spark plug in the fourth embodiment, which passes through the central axis of the spark plug. FIG. 10 is a diagram showing the relationship between the current frequency and the combined impedance Z in Experimental Example 1. FIG. 18 is a graph showing the relationship between the current frequency and the combined impedance Z for the sample 14 in Experimental Example 2. FIG. 18 is a graph showing the relationship between the current frequency and the combined impedance Z for the sample 15 in Experimental Example 2; FIG. 18 is a graph showing the relationship between the current frequency and the synthetic impedance Z for the sample 16 in Experimental Example 2. The figure which shows the evaluation result in Experimental example 2.

An embodiment of an ignition coil for an internal combustion engine will be described using FIGS. 1 to 5.
The ignition coil 1 for an internal combustion engine of the present embodiment is, as shown in FIG. 1, a coil main body 2 having a primary coil 11 and a secondary coil 12, and a cylindrical high pressure tower projecting from the coil main body 2 to the tip side. It has a portion 3, a joint portion 4, a first winding resistor 5, and a second winding resistor 6. The joint portion 4 is connected to the high pressure tower portion 3 and has a cylindrical shape extending to the tip side. The first winding resistor 5 is disposed in the high voltage tower 3 and electrically connected to the secondary coil 12. The second winding resistor 6 is disposed in the joint portion 4 and is electrically connected to the first winding resistor 5.

As shown in FIG. 3, the second winding resistor 6 includes a coil spring 7 that can be elastically extended and contracted in the axial direction Z. The coil spring 7 is disposed on the tip end side of the closely wound portion 71 in which the windings are in contact with each other in the axial direction Z via the insulating film 702 as shown in FIG. And a proximal elastic portion 73 disposed on the proximal end side of the closely wound portion 71 and elastically compressible in the axial direction Z. The closely wound portion 71 has a length of half or more of the entire length of the coil spring 7 in the axial direction Z.
In FIG. 1, the coil spring 7 is not a cross sectional view but a front view. Further, FIG. 3 shows a front view of the coil spring 7 in a free state.

The ignition coil 1 for an internal combustion engine can be used for an internal combustion engine such as a car or a cogeneration.
In addition, the side to which the spark plug in the ignition coil 1 for internal combustion engines is connected is made into a front end side, and the other side is demonstrated as a base end side.

  As shown in FIG. 1, the primary coil 11 and the secondary coil 12 are concentrically arranged on the inner and outer peripheries. A central core 13 is disposed inside the primary coil 11 and the secondary coil 12. Further, the outer peripheral core 14 is disposed so as to surround the outer periphery of the primary coil 11 and the secondary coil 12 in the direction orthogonal to the axial direction Z. The central core 13 and the outer peripheral core 14 constitute a magnetic path of a magnetic field generated by energization of the primary coil 11.

  The coil body 2 is formed by housing the primary coil 11 and the secondary coil 12 in a main body case 15 having an insulating property. In the body case 15, an igniter 16 for controlling energization of the primary coil 11 and interruption of the energization, and a magnet body 17 disposed between the central core 13 and the outer peripheral core 14 are also accommodated. There is.

  A high pressure tower portion 3 is formed so as to project from the main body case 15 to the tip side. The high voltage tower portion 3 has a high voltage output terminal 19 electrically connected to the secondary coil 12 through the connection terminal 18 disposed inside. The high voltage output terminal 19 is press-fit into the proximal end of the high pressure tower portion 3. Then, a region on the base end side of the high voltage output terminal 19 in the main body case 15 is filled with the filling resin 111 having electrical insulation, and the primary coil 11 and the secondary coil 12, the connection terminal 18, the central core 13, the outer periphery The core 14, the igniter 16, the magnet body 17 and the like are sealed.

  The first winding resistor 5 is inserted and disposed on the tip end side of the high voltage output terminal 19 in the high voltage tower portion 3. The first winding resistor 5 is in contact with the high voltage output terminal 19. Thereby, the first winding resistor 5 is electrically connected to the secondary coil 12 through the high voltage output terminal 19 and the connection terminal 18.

  As shown in FIG. 2, the first winding resistor 5 includes a core 51 that is an insulating magnetic body, and a conductor winding 52 that is spirally wound along the outer peripheral surface of the core 51. A pair of metal caps 53 are disposed at both ends of the core 51 in the axial direction Z and in contact with the conductor winding 52.

  The conductor winding 52 consists of a thin line. The conductor winding 52 is wound with a constant gap between adjacent lines in the axial direction Z. And between the adjacent lines in the axial direction Z in the conductor winding 52, a non-illustrated insulating coating material is disposed. Thereby, the conductor winding 52 is being fixed in the state in which the space | interval was formed between the lines adjacent to the axial direction Z. As shown in FIG. The metal cap 53 on the base end side of the pair of metal caps 53 is connected to the high voltage output terminal 19, and the metal cap 53 on the tip side is connected to the second winding resistor 6.

  As shown in FIG. 3, the second winding resistor 6 includes a coil spring 7 configured to be elastically stretchable in the axial direction Z. As shown in FIG. 5, the coil spring 7 is formed by winding a covered winding 70 made of a conducting wire 701 covered with an insulating film 702 all around. It should be noted that, in the portion where the coil spring 7 is electrically connected to another component (in the present example, the tip and the base end), the lead wire 701 of the coil spring 7 is exposed from the insulating film 702.

  The diameter of the conducting wire 701 can be larger than the diameter of the conductor winding 52 of the first winding resistor 5, for example, 0.45 to 0.8 mm. The electric resistance value of the lead wire 701 of the coil spring 7 is very small compared to the electric resistance value of the first winding resistor 5. The portion of the insulating film 702 covering at least the densely wound portion 71 has, for example, a thickness of 0.01 to 0.03 μm. In manufacturing the coil spring 7, first, the wire 701 in a state before being wound is covered with the insulating film 702 to form the covered winding 70, and then, this is wound. As a result, the conducting wires 701 can be reliably prevented from coming into contact with each other in the axial direction Z.

  As shown in FIG. 3, the coil spring 7 has a distal end elastic portion 72 at the distal end portion and a proximal end elastic portion 73 at the proximal end portion, and a closely wound portion 71 between the distal end elastic portion 72 and the proximal end elastic portion 73. Have.

  The distal end elastic portion 72 and the proximal end elastic portion 73 are wound such that a space is formed between adjacent winding lines in the axial direction Z at least in the free state. Thus, the distal end elastic portion 72 and the proximal end elastic portion 73 are configured to be elastically compressed in the axial direction Z in the free state.

  The closely wound portion 71 has a larger number of turns per unit length in the axial direction Z than the distal end elastic portion 72 and the proximal end elastic portion 73. As shown in FIG. 5, the closely wound portion 71 is densely wound so that the insulating films 702 of the coated winding 70 adjacent in the axial direction Z are in close contact with each other.

  As shown in FIG. 3, in the free state, in the coil spring 7, the length La of the closely wound portion 71 in the axial direction Z is half or more of the total length L of the coil spring 7 in the axial direction Z. Thus, the second winding resistor 6 (coil spring 7) is configured to ensure high inductance in the closely wound portion 71. The number of turns of the densely wound portion 71 is, for example, 85 to 120.

  As shown in FIG. 1, the coil spring 7 is disposed in a joint portion 4 connected to the high pressure tower portion 3. The joint 4 is fitted to the cylindrical joint main body 41 with the coil spring 7 disposed inside, the seal rubber 42 fitted to the base end of the joint main body 41, and the tip of the joint main body 41. And a rubber plug cap 43. The seal rubber 42 connects between the joint body 41 and the high pressure tower 3 while sealing them. Further, the spark plug is fitted into the plug cap 43 from the tip end side of the plug cap 43.

  The coil spring 7 is fixed in the axial direction Z with respect to the joint main body 41 in the closely wound portion 71 (not shown). Fixing of the coil spring 7 in the axial direction Z with respect to the joint main body portion 41 includes, for example, providing a locking portion projecting on the inner peripheral surface on the inner peripheral surface in a part of the joint main body portion 41 in the axial direction Z A part of the coil spring 7 at Z can be provided by providing a base stop part projecting to the outer peripheral side and locking them in the axial direction Z with each other.

  The coil spring 7 is positioned in the axial direction Z with respect to the joint main body portion 41 in a state where the proximal end elastic portion 73 is elastically compressed. The proximal end elastic portion 73 presses and holds the first winding resistor 5 to the proximal side by its elastic force (restoring force). The proximal end elastic portion 73 is electrically connected to the metal cap 53 of the first winding resistor 5. Thereby, the first winding resistor 5 and the second winding resistor 6 are electrically connected in series.

Next, the operation and effect of the present embodiment will be described.
An ignition coil 1 for an internal combustion engine has a first winding resistor 5 and a second winding resistor 6 connected in series. Therefore, a connection path 100 (hereinafter referred to simply as “connection” between the spark plug 8 connected to the ignition coil 1 and the coil body 2 and including the first winding resistor 5 and the second winding resistor 6 It is easy to increase the inductance in the path 100). Furthermore, the second winding resistor 6 is configured by the close winding portion 71 for half or more of the entire length thereof. Therefore, the inductance of the second winding resistor 6 can be increased. As a result, the inductance of the connection path 100 can be increased. As a result, the ignition coil 1 can obtain high impedance with respect to high frequency noise current in the connection path 100. On the other hand, since the frequency of the supply current supplied from the ignition coil 1 to the spark plug 8 is sufficiently small, the impedance for the supply current does not increase even if the inductance in the connection path 100 is large. As described above, since the impedance of the connection path 100 with respect to the noise current can be increased by the inductance component, the electric resistance component can be sufficiently reduced. Therefore, in the ignition coil 1, it is possible to secure a noise immunity (noise suppression performance) against noise current while realizing high output.

  In the closely wound portion 71 of the coil spring 7, the windings (coated winding 70) are in contact with each other in the axial direction Z via the insulating film 702. Therefore, shorting of the conductors 701 of the coated winding 70 in the axial direction Z can be prevented. Therefore, it is possible to prevent a change in inductance due to a short circuit between the conducting wires 701 and to easily wind the covered winding 70 closely in the close winding portion 71, and secure the inductance of the second winding resistor 6 (coil spring 7). Cheap.

  Further, Joule heat can also be suppressed by sufficiently reducing the electrical resistance component of the impedance as described above. Therefore, the deterioration of the ignition coil 1 due to heat can be suppressed, and the product life can be improved.

  The second winding resistor 6 is formed of a coil spring 7. Therefore, in addition to the role of giving inductance to the second winding resistor 6, it is also possible to have a role of stably electrically connecting the coil body 2 and the spark plug 8 connected to the ignition coil 1. . Therefore, the number of parts of the ignition coil 1 can be suppressed.

  In addition, the coil spring 7 is formed by winding a covered winding 70 made of a conducting wire 701 whose entire circumference is covered with an insulating film 702. Therefore, it is easy to wind tightly while securing insulation between the wires in the axial direction Z of the coated winding 70. Therefore, the densely wound portion 701 can be easily manufactured while securing the inductance. Moreover, the insulation between the coil spring 7 and the joint portion 4 can be secured. Therefore, generation of corona discharge can be suppressed between the coil spring 7 and the joint portion 4, and the life of the coil spring 7 and the joint portion 4 can be prolonged.

  As described above, in the present embodiment, noise current can be suppressed and high output can be achieved.

Second Embodiment
The present embodiment is an example in which the closely wound portion 71 is wound around a core 61 made of a magnetic material as shown in FIGS. In the present embodiment, the core 61 is an iron core. The densely wound portion 71 is wound around the core 61 in the entire axial direction Z. In the closely wound portion 71, the inner peripheral end of the winding is in contact with the outer peripheral end of the core 61 via an insulating film (not shown).

  Others are the same as in the first embodiment. In addition, the code | symbol same as the code | symbol used in already-appeared embodiment among the code | symbol used in Embodiment 2 or subsequent ones represents the component similar to the thing in already-appeared embodiment, etc., unless shown.

In the present embodiment, since the coil spring 7 is wound around the core 61, the inductance component of the impedance can be easily improved. Also in the present embodiment, the coil spring 7 is formed by winding the entire winding covered with the insulating film, so that the coil spring 7 is made of a material having conductivity such as an iron core. The winding 7 and the core 61 do not electrically short. Therefore, in order to secure the insulation between the winding of the coil spring 7 and the core 61, the core 61 does not have to be a relatively expensive insulating material such as ferrite and the like, and cost reduction can be easily achieved.
In addition, it has the same operation effect as Embodiment 1.

(Embodiment 3)
In this embodiment, in the first embodiment, a first peak frequency f1 at which the impedance of the first winding resistor 5 exhibits a peak value and a frequency at which the impedance of the second winding resistor 6 exhibits a peak value The second peak frequency f2 is adjusted. FIG. 8 is a diagram schematically showing the relationship between the current frequency and the impedance for each of the first winding resistor 5 and the second winding resistor 6. In FIG. 8, a line L5 schematically shows the relationship between the current frequency and the impedance of the first winding resistor 5, and the line L6 shows the current frequency and the impedance of the second winding resistor 6. It shows the outline of the relationship.

First, the first peak frequency f1 and the second peak frequency f2 will be described.
Each of the first winding resistor 5 and the second winding resistor 6 formed by winding the windings functions as an inductance, and windings adjacent to each other in the axial direction Z function as a capacitor. Therefore, each of the first winding resistor 5 and the second winding resistor 6 has a smaller function as an inductance and a larger function as a capacitor when the frequency of the flowing current is equal to or higher than a predetermined value. Therefore, as shown in FIG. 8, when the frequency of the current flowing through the first winding resistor 5 and the second winding resistor 6 is increased, the impedance peaks at a predetermined value of the current frequency, and from that point If the current frequency is further raised, the impedance gradually decreases. Thus, the frequency of the current when the impedance of the first winding resistor 5 peaks is the first peak frequency f1, and the frequency of the current when the impedance of the second winding resistor 6 peaks is the second The peak frequency is f2.

  In the present embodiment, a first peak frequency f1 which is a frequency at which the impedance of the first winding resistor 5 exhibits a peak value, and a second peak which is a frequency at which the impedance of the second winding resistor 6 exhibits a peak value The frequency f2 satisfies the relationship 0.65 ≦ f2 / f1 ≦ 1.05. That is, the first peak frequency f1 and the second peak frequency f2 have values close to each other to the extent that the above relationship (0.65 ≦ f2 / f1 ≦ 1.05) is satisfied. Furthermore, the first peak frequency f1 is 30 to 40 kHz.

The adjustment of the first peak frequency f1 and the second peak frequency f2 can be performed, for example, by adjusting the number of turns of the winding, the length, the coil cross-sectional area orthogonal to the axial direction Z, and the like.
Others are the same as in the first embodiment.

  In the present embodiment, the first peak frequency f1 and the second peak frequency f2 satisfy the relationship of 0.65 ≦ f2 / f1 ≦ 1.05. Therefore, the peak of the impedance of the first winding resistor 5 and the peak of the impedance of the second winding resistor 6 can be overlapped in the target frequency band among the frequencies of the current flowing through the connection path 100. Therefore, the impedance of the connection path 100 can be increased synergistically, for example in the frequency band in which the suppression of noise currents is particularly sought. Therefore, it is easy to suppress noise effectively.

The first peak frequency f1 is 30 to 40 MHz. When the noise current flowing through the connection path 100 has a relatively low frequency of about 30 to 40 MHz, the impedance component due to the inductance of the impedance of the connection path 100 tends to be small. On the other hand, sufficient noise current occurs in the frequency range of 30 to 40 MHz as noise at the time of ignition of the spark plug. Therefore, by setting the frequency f1 at which the impedance of the first winding resistor 5 exhibits a peak value to 30 to 40 MHz, the frequency 30 to 40 MHz can be effectively suppressed.
In addition, it has the same operation effect as Embodiment 1.

(Embodiment 4)
The present embodiment is an embodiment of an ignition device 1 having an ignition coil 1 for an internal combustion engine of Embodiment 3 and a spark plug 8 connected to the ignition coil 1 as shown in FIG.
As shown in FIG. 10, the spark plug 8 has a cylindrical housing 81 and a cylindrical insulator 82 held inside the housing 81 while exposing a part of the base end to the base end side of the housing 81. , A terminal fitting 83, a plug resistor 84, a center electrode 85, and a ground electrode 86. The terminal fitting 83 is held on the inside of the insulator 82 so that the base end portion protrudes. The plug resistor 84 is disposed on the tip end side of the terminal fitting 83 and inside the insulator 82. The center electrode 85 is on the tip side of the plug resistor 84 and is held inside the insulator 82 so that the tip portion protrudes. The ground electrode 86 forms a spark discharge gap 87 with the center electrode 85. The terminal fitting 83 is electrically connected to the coil spring 7. The combined electrical resistance value of the electrical resistance value of the first winding resistor 5 and the electrical resistance value of the plug resistor 84 is 1 to 3 kΩ.

  In FIG. 9, the coil spring 7 and the spark plug 8 are not cross sectional views but front views.

  As shown in FIG. 9, the spark plug 8 is fitted into the plug cap 43 from the front end side of the plug cap 43. The spark plug 8 is fitted in the plug cap 43 by bringing the outer peripheral surface of the portion of the insulator 82 exposed on the proximal end side of the housing 81 into contact with the inner peripheral surface of the plug cap 43 of the ignition coil 1. Then, when the spark plug 8 is fitted into the plug cap 43, the spark plug 8 is assembled to the ignition coil 1 while the terminal metal fitting 83 pushes the tip elastic portion 72 of the coil spring 7 in the axial direction Z for elastic compression. . Thereby, the conduction between the terminal fitting 83 and the coil spring 7 is secured.

  As shown in FIG. 10, a plug resistor 84 is disposed on the tip end side of the terminal fitting 83 in the spark plug 8 and inside the insulator 82 via a glass seal 88. The glass seal 88 is made of copper glass obtained by mixing copper powder (Cu) into glass. The plug resistor 84 is a cylindrical member obtained by sintering, in a furnace, a powdery resistor material mainly composed of glass mixed with carbon powder. In the present embodiment, the electrical resistance value of the plug resistor 84 is 1 kΩ or more. That is, in the present embodiment, the combined resistance value of the electrical resistance value of the first winding resistor 5 and the electrical resistance value of the plug resistor 84 is 1 to 10 while the electrical resistance value of the plug resistor 84 is 1 kΩ or more. It is assumed to be 3 kΩ.

  In the electrical path between the first winding resistor 5 and the center electrode 85, the electric resistance value of the portion excluding the first winding resistor 5 and the plug resistor 84 is less than 20 Ω.

  A center electrode 85 is disposed on the tip side of the plug resistor 84 in the spark plug 8 and inside the insulator 82 via a glass seal 88. A ground electrode 86 forming a spark discharge gap 87 with the center electrode 85 is disposed at the tip of the housing 81. The ground electrode 86 is opposed to the tip of the center electrode 85 in the axial direction Z. Thus, a spark discharge gap 87 is formed between the center electrode 85 and the ground electrode 86.

Next, the operation and effect of the present embodiment will be described.
In the present embodiment, the combined electrical resistance value of the electrical resistance value of the first winding resistor 5 and the electrical resistance value of the plug resistor 84 is 1 to 3 kΩ. That is, by attaching the spark plug 8 to the ignition coil 1 of Embodiment 1 capable of suppressing the noise current, the combined electrical resistance value of the first winding resistor 5 and the plug resistor 84 can be sufficiently reduced. Thereby, the output of the ignition coil 1 can be further increased. Furthermore, since Joule heat can be suppressed, deterioration of the ignition coil 1 and the spark plug 8 due to heat can be suppressed, and the product life can be improved.

Further, in the present embodiment, the electrical resistance value of the plug resistor 84 of the spark plug 8 is 1 kΩ or more. Therefore, the current flowing to the center electrode 85 and the ground electrode 86 of the spark plug 8 can be prevented from becoming too large, and the amount of electrode consumption of the center electrode 85 and the ground electrode 86 can be reduced.
In addition, it has the same operation effect as Embodiment 3.

(Experimental example 1)
This example is an example showing the influence on the noise suppression performance of the ignition device when the combined electrical resistance value of the first winding resistor and the plug resistor is changed as shown in FIG. In the present example and the following second experimental example, the combined electric resistance value of the first winding resistor and the plug resistor may be referred to as “combined electric resistance value Rs”.

  In this example, samples A and B described below were prepared. That is, the sample A and the sample B are igniters in which the first peak frequency f1 and the second peak frequency f2 do not satisfy the relationship of 0.65 ≦ f2 / f1 ≦ 1.05, and the synthesized electric currents are mutually different. The resistance value Rs is different. The sample A has a combined electric resistance value Rs of 1.4 kΩ, and the sample B has a combined electric resistance value Rs of 5.4 kΩ. That is, in the sample A and the sample B, the difference between the combined electrical resistance value Rs is 4 kΩ. The other basic structure is the same as that of the fourth embodiment.

  And in this example, the synthetic impedance between the first winding resistor and the center electrode when current of various frequencies is applied between the first winding resistor and the center electrode of each sample is It analyzed. The analysis results are shown in FIG. In FIG. 11, the broken line shows the result of synthetic impedance for sample A, and the solid line shows the result of synthetic impedance for sample B. In the present example and the following second experimental example, the combined impedance between the first winding resistor and the center electrode may be simply referred to as “combined impedance Z”.

  As can be seen from FIG. 11, the combined impedance Z with respect to the high frequency current flowing in each sample changes in substantially the same manner according to the frequency. However, in the band where the frequency of the current flowing to each sample is 80 MHz or less, the combined impedance Z for sample A is significantly lower than the combined impedance Z for sample B. This decrease increased particularly in the region where the current frequency was 30 to 40 MHz.

  From this result, it is understood that the igniter having a low combined electrical resistance Rs tends to have a particularly low combined impedance Z with respect to the current having a frequency of 30 to 40 MHz, as compared with the igniter having a high combined electrical resistance Rs.

  Therefore, in the fourth embodiment, the first peak frequency f1 and the second peak frequency f2 have a relationship of 0.65 ≦ f2 / f1 ≦ 1.05 while reducing the combined electrical resistance value Rs to 1 to 3 kΩ, Also, the first peak frequency f1 is 30 to 40 MHz. By this, in the fourth embodiment, while increasing the output of the ignition coil 1 by lowering the combined electric resistance value Rs, noise in which a decrease in the combined impedance Z may occur when the combined electric resistance value Rs is simply lowered. High impedance can be secured also for the current frequency band (30 to 40 MHz).

(Experimental example 2)
This example is an ignition device having the same basic configuration as that of the fourth embodiment, and as shown in FIGS. 12 to 15, the effect on noise suppression performance when f2 / f1 and the combined electric resistance value Rs are variously changed is It is an example analyzed and evaluated. In this example, the first peak frequency f1 is 32 MHz while the combined electrical resistance value Rs is relatively low. The frequency of 32 MHz is included in the frequency band (30 to 40 MHz) of current at which a drop in the combined impedance Z is concerned when the combined electrical resistance value Rs is lowered.

  In the present example, while the basic configuration is the same as that of the fourth embodiment, samples 1 to 28 in which f2 / f1 and the combined electrical resistance value Rs are variously changed are prepared. Here, f2 / f1 was variously changed in the range of 0.5 to 1.2. In the samples 1 to 28, the value of f2 / f1 was adjusted by adjusting the second peak frequency f2 while setting the first peak frequency f1 to 32 MHz. Here, in the samples 1 to 28, the first winding resistors are the same. The second peak frequency f2 was adjusted by adjusting the inductance of the second winding resistor 6. Moreover, about combined electrical resistance value Rs, it changed variously between 0.5-3.0 kohm.

  Further, while the basic configuration is the same as that of the fourth embodiment, the combined electrical resistance value Rs is higher than any of the samples 1 to 28 and the first peak frequency f1 and the second peak frequency f2 are 0.65 ≦ f2 / f1. A comparative sample not satisfying the relationship of ≦ 1.05 was also prepared. Specifically, the comparative sample has a first peak frequency f1 of 32.5 MHz, a second peak frequency f2 of 60.13 MHz, f2 / f1 of 1.85, and a combined electrical resistance value Rs of 5.4 kΩ.

  F2 / f1 of each sample, combined electric resistance Rs, electric resistance R1 of first winding resistor 5, first peak frequency f1, inductance L1 of first winding resistor 5, second peak frequency f2, second The inductance L2 of the two-winding resistor 6 and the electric resistance value Rr of the plug resistor 84 of the spark plug 8 are shown in Table 1.

  In this example, the synthetic impedance Z from the first winding resistor 5 to the center electrode 85 in each sample was analyzed according to the frequency of the current. The analysis results for sample 14 with f2 / f1 of 0.65 in FIG. 12, sample 15 with f2 / f1 of 1 in FIG. 13, and sample 16 with f2 / f1 of 1.05 in FIG. Are each represented by a solid line. Moreover, in FIGS. 12-14, the analysis result of a comparative sample is also represented with the broken line.

And evaluation of the noise suppression performance in sample 1-sample 28 was performed based on this analysis result. In the evaluation of the noise suppression performance in the samples 1 to 28, the peak value of the synthetic impedance Z in the area of the frequency of 30 to 40 MHz of the flowing current is larger than that of the comparative sample, and about 90% or more of the area In the above, it was determined whether or not the synthetic impedance Z was higher than that of the comparative sample. An evaluation result is shown in FIG. In the same figure, the thing whose synthetic | combination impedance Z is larger than a comparative sample was made into "(circle)", and the small thing was shown as "x".
For example, in samples 14 to 16 shown in FIG. 12 to FIG. 14, the peak value of the synthetic impedance Z in a region where the frequency of the current flowing is 30 to 40 MHz is larger than that of the comparative sample, and In the region of about 90% or more of the above, since the synthetic impedance Z is higher than that of the comparative sample, the evaluation is ○.

  As can be seen from FIG. 15, in the case of the current frequency of 30 to 40 MHz, when the combined electric resistance value Rs satisfies 1 to 3 kΩ and f2 / f1 satisfies 0.65 ≦ f2 / f1 ≦ 1.05, Evaluation was all ○. That is, in this case, it is possible to reduce the combined electric resistance value Rs to achieve high output of the ignition coil, and thereby, it is also possible to secure the noise current suppression performance of the frequency that may be aggravated.

  In addition, when the first peak frequency f1 and the second peak frequency f2 are the same, that is, f2 / f1 = 1, a high combined impedance is ensured even if the combined electrical resistance value is as small as 0.5 kΩ. can do. Therefore, by setting the first peak frequency f1 and the second peak frequency f2 to be the same, it is possible to further increase the output and secure noise suppression performance.

DESCRIPTION OF SYMBOLS 1 Ignition coil 11 Primary coil 12 Secondary coil 2 Coil main-body part 3 High-pressure tower part 4 Joint part 5 1st winding resistance body 6 2nd winding resistance body 7 Coil spring 71 Close winding part 72 Tip elastic part 73 Base end elasticity Section Z axis direction

Claims (6)

A coil body (2) having a primary coil (11) and a secondary coil (12);
A cylindrical high-pressure tower (3) protruding from the coil body (2) to the tip side,
A tubular joint (4) connected to the high pressure tower (3) and extending to the tip side;
A first winding resistor (5) disposed in the high pressure tower (3) and electrically connected to the secondary coil (12);
A second winding resistor (6) disposed in the joint portion (4) and electrically connected to the first winding resistor (5);
The second winding resistor (6) comprises a coil spring (7) elastically extendable in the axial direction (Z),
The coil spring (7) is disposed on the close winding portion (71) in which the windings are in contact with each other in the axial direction (Z) via the insulating film (702), and the tip side of the close winding portion (71) A distal end elastic portion (72) elastically compressible in the axial direction (Z), and a proximal end elastic portion (73) which is disposed on the base end side of the closely wound portion (71) and elastically compressible in the axial direction (Z) Have and
An ignition coil (1) for an internal combustion engine, wherein the closely wound portion (71) has a length of half or more of the entire length of the coil spring (7) in an axial direction (Z).   The internal combustion engine according to claim 1, characterized in that the coil spring (7) is formed by winding a covered winding (70) consisting of a conducting wire (701) whose entire circumference is covered with the insulating film (702). Ignition coil for engines (1).   The ignition coil (1) for an internal combustion engine according to claim 1 or 2, wherein the closely wound portion (71) is wound around a core (61) made of a magnetic material.   The first peak frequency f1 which is a frequency at which the impedance of the first winding resistor (5) shows a peak value, and the second peak which is a frequency at which the impedance of the second winding resistor (6) shows a peak value The ignition coil (1) for an internal combustion engine according to any one of claims 1 to 3, wherein the frequency f2 satisfies the relationship 0.65 0.6 f2 / f1 5 1.05.   The first peak frequency f1 of the current when the impedance of the first winding resistor (5) is maximum is 30 to 40 MHz, according to any one of claims 1 to 4, Ignition coil for internal combustion engines (1). An ignition device (10) comprising an ignition coil (1) for an internal combustion engine according to any one of the preceding claims and a spark plug (8) connected to the ignition coil (1) ,
The spark plug (8) has a cylindrical housing (81) and a cylinder held inside the housing (81) while exposing a part of the base end to the base end side of the housing (81). -Shaped insulator (82), a terminal fitting (83) held inside the insulator (82) so that the base end portion protrudes, and the tip end side of the terminal fitting (83), The plug resistor (84) disposed inside the insulator (82), and the tip end side of the plug resistor (84), the tip end portion being held inside the insulator (82) so that the tip portion protrudes A central electrode (85) and a ground electrode (86) forming a spark discharge gap (87) between the central electrode (85) and the central electrode (85);
The terminal fitting (83) is electrically connected to the coil spring (7),
Ignition for an internal combustion engine characterized in that the combined electric resistance value of the electric resistance value of the first winding resistor (5) and the electric resistance value of the plug resistor (84) is 1 to 3 kΩ. Device (10).

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