JP3627594B2 - Ignition coil - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
INDUSTRIAL APPLICABILITY The present invention is used for an ignition coil, a high voltage transformer, etc. in which a primary body and a secondary coil and a magnetic material are attached to the gap between them, and in particular, a line voltage in the secondary coil, insulation between the primary coil and the secondary coil. The present invention relates to an ignition coil that requires a high withstand voltage, such as distance, collapse of a boundary surface between a secondary coil bobbin and an electric wire layer, and a winding method thereof.
[0002]
[Prior art]
Conventional secondary windings such as ignition coils and high-voltage transformers are known as so-called skew windings in order to improve insulation characteristics, space efficiency, winding time reduction, and the like. As shown in FIG. 2, the wire supply nozzle 200 is moved back and forth while winding the secondary bobbin 100a, starting from the low pressure side collar 102a to form a substantially triangular slope, along the slope. Winding and winding up to the high-pressure collar 101a. In Japanese Patent Application Laid-Open No. 9-129460, winding is started from the low pressure side to form a substantially triangular slope, and then continuously wound up to a predetermined winding height. The diameter is reduced to a reduced shape, the line voltage on the high voltage side, and the insulation distance from the primary bobbin are increased to improve the insulation characteristics. Further, in Japanese Patent No. 2630716, a predetermined number of forward windings and a predetermined number of backward windings are sequentially repeated alternately from one end to the other end of the secondary bobbin, and the winding start and winding ends are repeated at the winding height. There is a method for improving the insulation characteristics by reducing the thickness. Alternatively, Japanese Patent Laid-Open No. 9-246075 discloses a publication in which the inner diameter of the secondary bobbin gradually increases from one end to the other end, the thickness gradually decreases, and the number of turns gradually increases. Next, Japanese Patent Application Laid-Open No. 9-69455 discloses that the inclination angle is 6 ° or more and 20 ° or less for the purpose of defining the inclination angle of a substantially triangular shape for reducing the line voltage. As for the bobbin shape, there is a method of forming a slant surface of oblique winding by previously forming a down-gradient slope along the traveling direction from the winding start end into a bobbin as in JP-A-60-107815. .
[0003]
[Problems to be solved by the invention]
In the oblique winding, since the winding layers are continuously laminated on the inclined surface, the winding disturbance generated as the winding progresses tends to increase at the end of winding.
[0004]
In addition, as shown in FIG. 7B, unlike the skew winding according to the present invention, the secondary bobbin is partitioned by an insulating partition at regular intervals by a winding method that has been conventionally performed. After winding a predetermined number of wires between the partition walls, a method of sequentially winding the wires over the adjacent windings, in a so-called divided winding, a measurement lead wire is taken out from the secondary winding, and each measurement site and voltage are The relationship was measured. As shown in FIG. 7 (a), as a result of measuring the potential from the low pressure side to the high pressure side, the voltage should increase in proportion to the number of turns. The high frequency component of about several MHz in the middle tends to concentrate on the high voltage side, that is, the voltage per turn is relatively higher on the high voltage side than on the low voltage side.
[0005]
In Japanese Patent Application Laid-Open No. 9-129460, the diameter is reduced as the coil is wound on the high voltage side, the slope length of the inclined surface is reduced to reduce the line voltage, and if the winding is small, the slope length is reduced. Although there is an effect, large turbulence may propagate, which is particularly problematic on the high-pressure side where the insulation characteristics are severe. Further, as a method of obtaining high insulation characteristics by reducing the diameter of the high-pressure side and the low-pressure side, as in Japanese Patent No. 2630716, the total number of turns in the forward path and the return path is always kept constant, and the winding is sequentially repeated. However, the number of turns in the forward path and the return path is limited to a certain value or less in order to ensure a line withstand voltage. Then, if the number of reciprocating turns is set small in consideration of the high voltage side where the line voltage is relatively large, it is necessary to perform more windings on the low voltage side, and the bobbin length tends to be long. Next, the inclination angle of the skew winding is set to 6 ° to 20 ° in Japanese Patent Laid-Open No. 9-69455, but this is not an absolute condition for winding but an example satisfying various constraints. For example, even if the inclination angle is less than 6 degrees, it is possible if the number of turns can be reduced. Regarding the publication in which the inner diameter of the secondary bobbin in JP-A-9-246075 gradually increases from one end to the other end, the thickness gradually decreases, and the number of turns gradually increases, the central part of the bobbin has the same diameter and the high-pressure side end, or It can be said that reducing the diameter by reducing the winding height only at the low-pressure side end is different from the gradual increase and decrease of the publication. Next, regarding the shape of the bobbin, Japanese Patent Application Laid-Open No. 60-107815 uses an inclined surface formed on the bobbin for the inclination angle of the oblique winding, which is effective with a constant inclination angle specification, but the angle is slightly changed. There is a problem that it is necessary to make a new one when you want.
[0006]
[Means for Solving the Problems]
In order to solve the above-described problem, in the first invention, by starting winding from the high-pressure side instead of from the low-pressure side, it is possible to arrange a portion with less winding disturbance on the high-pressure side. Further, when the forward winding and the backward winding are repeated gradually in the low-pressure direction, a downwardly inclined surface θ (FIG. 4) corresponding to the amount of forward winding is formed. Furthermore, when the amount of unwinding of the return winding is made a predetermined number less than that of the outward winding, the position of the winding end surface on the high voltage side gradually shifts from the high voltage side toward the low pressure side according to the difference, and the winding height and reciprocation The number of turns gradually increases, and a slope of slope [theta] 1 (FIG. 4) is formed. In this way, since the number of turns on the inclined surface on the high voltage side can be controlled to be small, it is possible to make an ignition coil with good withstand voltage characteristics by keeping the line voltage low.
[0007]
In the second invention, while the inclination angle θ in the traveling direction is less than 6 °, by controlling the inclination angle and the number of turns of the upward slope θ1 going from the high pressure side to the low pressure side in the first invention, There is a synergistic effect of keeping the number of reciprocating turns low and preventing collapse by a gentle inclination angle θ.
[0008]
In the third aspect of the invention, the slope angle θ1 of the upward slope from the high pressure side to the low pressure side is determined by the line distance Pt (FIG. 4) and the shift amount s (FIG. 5). It can be set arbitrarily within the allowable range to improve the insulation performance.
[0009]
The fourth aspect of the invention is suitable for use in the case of optimal adjustment according to the potential distribution on the high voltage side.
[0010]
In the fifth aspect of the invention, a stepped shape with a simple shape can be obtained by controlling the winding height on the high voltage side to be lower than the allowable line voltage, distributing the remaining number of windings to the low voltage side, and winding. .
[0011]
In the sixth aspect of the present invention, when a rib, which is a member that gradually decreases the height of the bobbin from the beginning of winding toward the low pressure side, is installed, the section on which the rib is installed can be regarded as a substantially polygonal bobbin. Since the upper rotation speed slightly increases or decreases depending on the rotation angle, there is an effect of winding the electric wire. In addition, because there is a gap between the ribs, defects such as voids occur when the bobbin after winding is filled with, for example, epoxy resin and cured, and the penetration to the lowermost layer on the high-pressure side, which has strict insulation properties, is not sufficient This has the effect of preventing
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, examples illustrating the embodiments of the present invention will be described with reference to the drawings.
[0013]
(First Embodiment) The first embodiment will be described with reference to FIGS.
[0014]
In FIG. 3, the ignition coil is a transformer mainly composed of a cylindrical secondary coil 205, a primary coil 206, and an iron core (not shown). When the current flowing through the primary coil 206 is cut off, a voltage proportional to the number of turns between the primary and secondary coils is induced in the secondary coil 205 by magnetic induction. The secondary coil voltage in this embodiment is, for example, 30 kV. Next, although not shown, the ignition coil is generally inserted into the plug hole of the engine, and the high voltage side of the coil is generally engaged with the electrode of the plug. A secondary electrode is installed on the side. Also, since the electromagnetic core material is mounted concentrically between the bobbin and between the primary and secondary coils to double the electromagnetic induction action, the high pressure side of the bobbin is sealed, while the low pressure side far from the plug is As a structure in which the inner diameter of the bobbin is opened and a rotating shaft is inserted when the secondary bobbin is wound, the high pressure side and the low pressure side are distinguished by the bobbin shape.
[0015]
FIG. 2 is a diagram showing a conventional example of the winding of the secondary coil. The winding to the secondary bobbin starts from the low-pressure side collar 102a, which is close to the rotating shaft (not shown) inserted from the low-pressure side. It is common. Next, an appropriate substantially triangular slope is formed at the beginning of winding, and the oblique winding is repeated along the slope to advance at a predetermined winding height H. The method is such that the winding is finished while leaving the wire, or the diameter is reduced by a method of shortening the slope length while gradually reducing the number of reciprocating turns (not shown), and the line voltage on the high voltage side is kept low.
[0016]
In FIG. 1, the rotating shaft (not shown) is inserted from the low pressure side as in FIG. 2, but the winding is started from below the wall surface of the high pressure side collar 101 of the secondary bobbin 100, contrary to FIG. 2. This is for the characteristic that winding disturbance increases as the winding progresses, in order to arrange the side with a smaller number of turns on the high-pressure side and to change the number of turns on the high-pressure side and the inclination angle θ as appropriate. Next, while increasing the number of turns of the forward winding and the backward winding gradually while increasing the number of windings of the forward winding and the backward winding in a direction opposite to the outward winding in a direction opposite to the forward winding, A winding layer having a downwardly inclined slope θ is formed in the direction toward θ1 and the low pressure side, and the process is repeated until the winding height becomes h at P1. Thereafter, the winding height h is formed up to P2, the last forward winding is performed from P2 so that P3 is finished, and the winding is finished.
[0017]
Next, details of the winding will be described with reference to FIGS. First, numerals 1, 20, 36... 696 in FIG. 4 indicate the total number of windings from the start of winding. The forward winding is 1 to 20, 37 to 72, and the backward winding is 21 (not shown) to 36, or 73 (not shown) to 104, etc. Therefore, one round trip between the forward path and the return path is 1 → 20 → 36 or 37 → 72 → 104. In FIG. 5, the winding sequence changes as 1 → 20 → 36 → 37 → 72 → 104. The actual number of turns at that time, as shown in FIG. 5 (b), starts with 20 turns in the forward direction → 16 turns in the return direction → 36 turns in the forward direction → 32 turns in the return direction → 52 turns in the outward direction. In addition, the inward winding forms a tilt angle θ1 by shifting in the low-pressure direction with a number of turns that is four turns less than the outward winding. θ1 is determined by the shift amount s, that is, the winding pitch Pt. In this embodiment, θ1≈tan ⁻¹ (2 × wire diameter / 4 × Pt).
[0018]
Next, in FIG. 4, the inclination angle θ in the low-pressure side direction is determined in advance in the forward winding (for example, 1.2 mm), and this is set as one unit of the winding advance shift amount in the low-pressure side direction. . In the embodiment, the winding pitch Pt is 0.06 mm, and winding is performed every 20 turns. Regardless of the number of turns in the return path, θ decreases by two layers when the winding width W is advanced, and θ≈tan ⁻¹ (2 × electric wire diameter / W).
[0019]
When θ is measured with an actual winding bobbin, it is about 5 ° when W = 1.2 mm and the wire diameter is 0.058 mm, which is almost equal to the calculated value of 5.52 °. That is, θ can be less than 6 degrees under this winding condition. With respect to the inclination angle θ1, when measured with an actual winding bobbin (not shown) with 20 turns for the forward winding and 10 turns for the backward winding, for example, it is approximately 10 ° and substantially coincides with the calculated value 10.9.
[0020]
(Second Embodiment) A second embodiment will be described with reference to FIGS.
[0021]
In the so-called split winding conventionally performed as shown in FIG. 7B, the secondary bobbin 100b is partitioned by an insulating partition 210 at regular intervals, and a predetermined number of windings are wound between the partitions. FIG. 7A shows a measurement lead wire taken out from the secondary winding of the bobbin that has been wound sequentially while passing over the winding portion, and the relationship between each measurement site and the voltage measured. As a result of measuring the potential from the low-voltage side to the high-voltage side from the measurement site 0 to 10, for example, the frequency component of 10 kHz is almost constant at any site, but at about 2.5 MHz, the potential concentrates more at the specific site on the high-voltage side. I understood that. That is, it was found that the voltage per turn is relatively higher on the high voltage side than on the low voltage side. Therefore, referring to FIG. 7A, the line voltage can be optimized by forming a parabola-like inclined surface that matches the potential distribution of the bobbin in FIG. The winding method can be realized by gradually reducing the shift amount s in FIG.
[0022]
Next, the extra line 105 is provided for the purpose of finely adjusting the total number of turns. In other words, winding of the winding end slope is not performed because the insulation characteristics are deteriorated and the winding pitch is increased in the middle of the slope because the insulation characteristics are deteriorated. The number of turns can be adjusted with a wire. In this case, the problem of the line voltage due to the collapse of the winding layer, which is a problem at the brim boundary, is not a problem if the number of layers is within a range that satisfies the predetermined line voltage even if it collapses.
[0023]
(Third Embodiment) A third embodiment will be described with reference to FIG.
[0024]
In the figure, an example is shown in which winding is started at a constant winding height h1 from the high-pressure side collar 101g, and then wound at a winding height h2 from a certain point in time. First, the winding design can be simplified by setting h1 from the number of turns satisfying the line voltage on the high voltage side and allocating the remaining number of turns to h2.
[0025]
(Fourth Embodiment) A fourth embodiment will be described with reference to FIG.
[0026]
The present embodiment relates to the shape of the bobbin. In the figure, ribs 300 are radially arranged on the circumferential surface of the secondary bobbin in the vicinity of the high-pressure side collar 101f (for example, eight or more), and the height gradually increases as the high-pressure side collar 101f is approached. It has become. When winding is started from the high voltage side, the winding surface can be regarded as a substantially polygonal shape, so that the rib 300 exhibits a winding tightening effect and the winding is stabilized. Furthermore, in the post-winding process, epoxy resin is injected into the winding bobbin and sealed and hardened, but when the wires are stacked in multiple layers with a narrow line distance, the resin is less likely to penetrate into the lower layer. There is a possibility that voids or the like are generated from the portion, resulting in dielectric breakdown. However, since there is a gap between the ribs 300, the epoxy resin can easily penetrate even in the lowermost layer.
[0027]
【The invention's effect】
As described above, according to the present invention, since the winding start is on the high voltage side, the winding part with less winding disturbance can be placed on the high voltage side, and the number of turns in the vicinity of the high voltage side end is gradually increased. Since the inclined surface is formed, the pressure resistance can be improved. Further, the diameters of both the high-voltage side and the low-voltage side are reduced to minimize the height of the winding layer near the collar, so that a breakdown voltage failure due to the collapse of the layer that occurs near the collar does not occur.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a first embodiment of the present invention.
FIG. 2 is a cross-sectional view showing a conventional example of an ignition coil.
FIG. 3 is a partial cross-sectional view of an ignition coil.
FIG. 4 is a cross-sectional view for explaining an ignition coil.
FIG. 5 is a partially enlarged view of a cross section for explaining an ignition coil.
FIG. 6 is a cross-sectional view showing a second embodiment of the present invention.
FIG. 7 is a diagram showing a relationship between an output voltage of an ignition coil and a measurement site.
FIG. 8 is a diagram showing a third embodiment of the present invention.
FIG. 9 is a sectional view showing a fourth embodiment of the present invention.
[Explanation of symbols]
100 ... Bobbin, 101 ... High pressure side collar, 102 ... Low pressure side collar,
103: Distance between lines, 104: Electric wire, 105 ...
200 ... Nozzle, 205 ... Secondary winding, 206 ... Primary winding 300 ... Rib, .theta.
θ1… Inclination angle of the high-pressure-side rising slope, H, h… winding height,
Pt: winding pitch, s: shift amount,

Claims (12)

In an ignition coil including a secondary coil in which a wire rod is wound obliquely with respect to the axis of the coil on a bobbin,
The secondary coil is advanced by a predetermined number of turns in the forward winding, with the wire coil starting from the side close to the plug with the ignition coil on the bobbin inserted into the plug hole of the engine. Ignition coil characterized in that it is a coil that is rewound with a small number of turns, and has an increased number of turns for forward and return turns. In claim 1,
An ignition coil characterized in that the position of the winding end surface on the side close to the plug in the state where the ignition coil on the bobbin is inserted into the plug hole of the engine forms an inclination angle. In claim 1,
An ignition coil characterized in that the position of the winding end face on the side far from the plug in the state where the ignition coil on the bobbin is inserted into the plug hole of the engine forms an inclination angle. In claim 3,
The tilt angle is 6 An ignition coil characterized by being less than a degree. In an ignition coil including a secondary coil in which a wire rod is wound obliquely with respect to the axis of the coil on a bobbin,
The bobbin has a secondary electrode;
The secondary coil has the side on which the secondary electrode is formed on the bobbin as the start of winding of the wire, is advanced by a predetermined number of turns in the forward winding, and is rewound by the return winding of the number of turns smaller than the forward winding, An ignition coil characterized in that the coil has an increased number of turns for forward winding and backward winding. In claim 5,
An ignition coil characterized in that the position of the winding end face on the side where the secondary electrode is formed on the bobbin forms an inclination angle. In claim 5,
An ignition coil characterized in that the position of the winding end face on the side opposite to the side where the secondary electrode is formed on the bobbin forms an inclination angle. In claim 7,
The tilt angle is 6 An ignition coil characterized by being less than a degree. In an ignition coil including a secondary coil in which a wire rod is wound obliquely with respect to the axis of the coil on a bobbin,
The bobbin has one end sealed and the other end open.
The secondary coil starts winding the wire on the sealed side of the bobbin, is advanced by a predetermined number of turns in the forward winding, is rewound by a return winding having a smaller number of turns than the forward winding, An ignition coil characterized by being a coil having an increased number of turns. In claim 9,
An ignition coil characterized in that a position of a winding end face on a sealed side of the bobbin on the bobbin forms an inclination angle. In claim 9,
An ignition coil characterized in that a position of a winding end face on the open side on the bobbin forms an inclination angle. In claim 11,
The tilt angle is 6 An ignition coil characterized by being less than a degree.

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