JP3055934U - Ignition coil for internal combustion engine - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To reduce the size of a secondary coil by eliminating the need for a waste winding groove. SOLUTION: The ignition coil for an internal combustion engine according to the present invention is characterized in that approximately the same number of turns is applied to each divided groove 5 of a secondary bobbin 2 for winding a secondary coil 2a.

Description

[Detailed description of the invention]

[0001]

[Technical field to which the invention belongs]

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

[0002]

[Prior art]

 FIG. 6 is a cross-sectional view of a conventional ignition coil for an internal combustion engine (hereinafter, referred to as an "ignition coil"). In the drawing, a conventional ignition coil has a primary coil 101a wound around an outer periphery and an iron core 103 penetrating around the inner periphery, and a secondary coil 102a wound around a concentric outer side of the primary coil bobbin 101. The secondary coil bobbin 102 is housed in an insulating case 104 having an opening at the bottom and a case opening 120 on the side opposite to the bottom, and the opening at the bottom is formed at one end 101 m of the primary coil bobbin 101. The primary and secondary coils 101a and 102a and the iron core 103 are fixed in the insulating case 104 with a thermosetting resin 108 which is closed and poured into the insulating case 104 and hardened. The iron core 103 is composed of two laminated iron cores of silicon steel plates having a substantially U-shape. One end of each of the two laminated iron cores is disposed inside the primary coil bobbin 101, and the other is disposed on the outer wall of the insulating case 104. They are joined by adhesive or welding, etc., facing each other, and constitute a magnetic circuit that forms a closed magnetic circuit as a whole.

Each of the bobbins 101 and 102 is formed of an electrically insulating material such as a synthetic resin, and the secondary coil bobbin 102 has narrow dividing grooves 151 and 152 at both ends in the longitudinal direction thereof, and a gap therebetween. Eight divided grooves 150 having a predetermined width are formed, and each of these divided grooves 150, 151, 152 of the secondary coil bobbin 102 has a winding ratio of, for example, 1:80 to 120 with respect to the primary coil 101a. The secondary coil 102a is wound.

The insulating case 104 is formed of an insulating material such as a synthetic resin. A primary terminal (not shown) is provided at one end of the case opening 120 of the insulating case 104 in the longitudinal direction (perpendicular to the plane of FIG. 6). ), And a high-voltage terminal (not shown) is provided at the other end.

[0005] Furthermore, the primary coil 101a and the primary terminal are electrically connected at a connection portion P1, and the secondary coil 102a and the high voltage terminal are electrically connected at a connection portion Q1, respectively. After a predetermined current is applied to the primary coil 101a, When cut off, the high voltage current generated in the secondary coil 102a is supplied from the high voltage terminal to the ignition plug via the high tension cord.

[0006] The high voltage until the spark plug generates a spark discharge is almost uniformly distributed to the entire secondary coil 102a, but at the moment when the spark discharge occurs, the sharp potential change causes the secondary voltage to increase. The voltage distribution at both ends (start and end of winding) of the next coil 102a increases. Therefore, in order to alleviate the voltage distribution that increases at both ends of the secondary coil 102a, the narrow dividing grooves 151 and 152 (particularly, the dividing groove 152 located at the high voltage side) located at both ends of the secondary coil bobbin 102 described above. Is smaller than the number of windings in the other divided grooves 150.

[0007]

[Problems to be solved by the invention]

 However, even when the number of windings of the dividing grooves 151 and 152 at both ends of the secondary coil bobbin 102 is reduced as in the above-described conventional ignition coil, the dividing grooves 151 and 152 for that purpose are also secured as so-called discarded winding grooves. Therefore, a space is required for the number of windings, which is a wasteful space, which hinders the miniaturization (reduction in length) of the secondary coil 102a.

When the number of windings of the dividing grooves 151 and 152 at both ends of the secondary bobbin 102 is reduced, the number of windings of the other dividing grooves 150 is increased by the reduced amount, and the winding height is increased. Therefore, the outer diameter of the secondary coil 102a is increased, which also prevents the secondary coil 102a from being downsized.

This invention has been proposed in view of the above, and an object of the invention is to provide an ignition coil for an internal combustion engine capable of reducing the size of a secondary coil by eliminating the need for a waste winding groove.

[0010]

[Means for Solving the Problems]

 In order to achieve the above object, according to the present invention, in the ignition coil for an internal combustion engine that supplies a high voltage to the ignition plug of the internal combustion engine and generates spark discharge, each divided groove of the secondary bobbin around which the secondary coil is wound is provided. It is characterized by applying almost the same number of turns.

[0011]

[Embodiment of the invention]

 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view showing the ignition coil of the present invention, and FIG. 2 is a sectional view taken along line AA of FIG. In these figures, the ignition coil of the present invention supplies a high voltage to an ignition plug of an internal combustion engine to generate spark discharge. A primary coil 1a is wound around the outer periphery, and an iron core 3 passes through the inner periphery. A primary coil bobbin 1 and a secondary coil bobbin 2 around which a secondary coil 2a is wound and disposed concentrically outside the primary coil bobbin 1 have an opening at the bottom and a case opening at the side opposite to the bottom. The primary coil bobbin 1 is housed in an insulating case 4 and one end 1 m of the primary coil bobbin 1 is closed at the bottom opening. 2a and an iron core 3 are fixed in an insulating case 4.

The iron core 3 is composed of two laminated iron cores made of substantially U-shaped silicon steel sheets, each end face of the two laminated iron cores, one set being inside the primary coil bobbin 1, and the other set being an insulating case. 4 are joined to each other on the outer wall side by an adhesive, welding, or the like, and constitute a magnetic circuit forming a closed magnetic circuit as a whole.

Each of the bobbins 1 and 2 is formed of an electrical insulating material such as a synthetic resin, and the secondary coil bobbin 2 is formed with eight divided grooves 5 having a predetermined width in the length direction thereof. In each of these divided grooves 5 of the secondary coil bobbin 2, the same number of secondary coils 2a having a winding ratio of, for example, 1:80 to 120 with respect to the primary coil 1a are wound.

The insulating case 4 is formed of an insulating material such as a synthetic resin. A primary terminal 6 is provided at one end of the case opening 12 of the insulating case 4 in the longitudinal direction (X direction in FIG. 1), and the other end is provided at the other end. Each of the high-voltage terminals 7 is provided.

Further, the primary coil 1a and the primary terminal 6 are electrically connected at a connection portion P, and the secondary coil 2a and the high voltage terminal 7 are electrically connected at a connection portion Q, so that a predetermined current flows through the primary coil 1a. When the power is cut off after the power is supplied, the high voltage current generated in the secondary coil 2a is supplied from the high voltage terminal 7 to the ignition plug via the high tension cord.

The high voltage until the spark discharge is generated in the spark plug is almost uniformly distributed to the entire secondary coil 2 a, ie, each of the divided grooves 5. Due to such a potential change, the shared voltage at both ends (start and end of winding) of the secondary coil 2a increases. Next, the shared voltage will be described.

FIG. 3 is a diagram showing an equivalent circuit of the secondary coil. In the figure, S1, S2,..., And S8 are sections 1 (S1) in which the divided grooves 5 of the secondary coil 2a shown in FIG. 2 are arranged in order from the upper side (low pressure side) to the lower side (high pressure side). ), Section 2 (S2),..., Section 8 (S8). Each section S1 to S8 of the equivalent circuit is represented by a resistor R, a coil L, and a capacitor C.

FIG. 4 is a diagram showing a shared voltage in each section calculated using the equivalent circuit of FIG. 3, and FIG. 5 is a diagram showing an interlayer voltage obtained from the shared voltage. In these figures, the solid line shows the case of the secondary coil 2a of the present invention wound by the same number in each divided groove, and the broken line shows a conventional point having a so-called discarded winding groove in which the number of turns of the secondary coil end grooves is reduced. The case of a fire coil is shown.

Assuming that the discharge starting voltage at the moment when the spark discharge occurs is 25 kV, the shared voltage E in each section at the start of the discharge is calculated using the above-described equivalent circuit, as shown in FIG. become. In FIG. 4, the sharing voltage E is represented by a sharing ratio (%) to the entire voltage.

In the case of the conventional ignition coil in which the number of turns in the both-end grooves of the secondary coil is reduced, the shared voltage E of the both-end grooves (section 1, section 8) is certainly low, but the adjacent sections 2, 2 On the other hand, the shared voltage E of 7 is increased. Further, the potential difference per turn (one turn), that is, the interlayer voltage Δe between adjacent electric wires, which is obtained by dividing the shared voltage E by the number of turns of the section, is shown in FIG. In particular, in the section 8 on the high pressure side where the number of turns is small, it is very high.

On the other hand, in the case of the secondary coil 2a of the present invention in which the winding is uniformly applied to all the divided grooves, the shared voltage ΔE of the grooves at both ends (section 1, section 8) is slightly higher as shown in FIG. However, the number of turns in that section is the same as that of the other sections and is considerably larger than before, so the voltage per turn, that is, the interlayer voltage Δe between adjacent wires is As shown in FIG. 5, a low value can be stably maintained throughout, including the high-pressure side section 8, so that a layer short between the electric wires can be reliably prevented.

As described above, in this embodiment, all the divided grooves 5 of the secondary coil bobbin 2 have the same width and the same number of windings, so that the so-called discarded winding grooves conventionally provided are omitted. Therefore, the length direction of the secondary coil bobbin 2 can be shortened.

In addition, since winding can be performed evenly on each of the divided grooves 5, the winding height can be suppressed so as not to increase over the whole, and the radial direction of the secondary coil 2 a can also be shortened. As described above, both the length direction and the radial direction of the secondary coil 2 can be shortened, which can greatly contribute to downsizing of the secondary coil 2a.

In addition, since the interlayer voltage Δe in each of the divided grooves 5 can be kept low throughout, it is possible to reliably prevent a layer short-circuit between electric wires, and therefore, it is necessary to use a highly reliable ignition coil. can do.

[0025]

[Effect of the invention]

 As described above, according to the ignition coil for an internal combustion engine of the present invention, since the number of turns of all the divided grooves of the secondary bobbin is made substantially the same, the so-called discarded winding grooves conventionally provided can be omitted. Therefore, the length direction of the secondary bobbin can be shortened. In addition, since the winding can be performed almost evenly in each of the divided grooves, the winding height can be suppressed so as not to be high over the whole, and the radial direction of the secondary coil can be shortened. As described above, both the length direction and the radial direction of the secondary coil can be shortened, which can greatly contribute to downsizing of the secondary coil.

Further, since the interlayer voltage in each of the divided grooves can be kept low throughout, it is possible to reliably prevent a layer short circuit between the electric wires, and therefore, to make the ignition coil highly reliable. Can be.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an ignition coil of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a diagram showing an equivalent circuit of a secondary coil.

FIG. 4 is a diagram showing a shared voltage in each section calculated using the equivalent circuit of FIG. 3;

FIG. 5 is a diagram showing an interlayer voltage obtained from a shared voltage in each section.

FIG. 6 is a sectional view of a conventional ignition coil.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Primary coil bobbin 1a Primary coil 2 Secondary coil bobbin 2a Secondary coil 3 Iron core 4 Insulating case 5 Dividing groove 6 Primary terminal 7 High voltage terminal 8 Thermosetting resin 12 Case opening E Sharing voltage L coil P connection part Q connection part Δe interlayer Voltage

Claims (2)

[Utility model registration claims] 1. An internal combustion engine ignition coil for supplying a high voltage to an ignition plug of an internal combustion engine to generate spark discharge, wherein substantially the same number of turns is applied to each of the divided grooves of a secondary bobbin for winding a secondary coil. An ignition coil for an internal combustion engine, wherein the ignition coil is applied. 2. The ignition coil for an internal combustion engine according to claim 1, wherein each of the divided grooves has a substantially equal width.