KR100242545B1 - Ignition Coil - Google Patents

Abstract

Discussed is the smallest size ignition coil with no performance degradation under small primary currents. The ignition coil magnetizes the iron core 1, which forms a closed magnetic circuit through the air gap 2, a permanent magnet 4 magnetized in a direction opposite to the magnetization direction by the primary winding current, and the iron core 1 To include a primary winding 6 wound around the iron core 1. The cross-sectional area SG of the iron core 1 into which the permanent magnet is inserted is made substantially the same as the cross-sectional area SM of the permanent magnet 4. In order to bias the permanent magnet 4 to 2/3 of the magnetic flux saturation point of the iron core 1, the permanent magnet has a thickness (LM) satisfying 0.6 mm <LM <1.8 mm and 1.3 <SM / SF <3.0. It shall be shaped so as to have a cross sectional area (SF) of the core winding part and a cross sectional area (SM) of the permanent magnet.

Description

Ignition Coil

1 is a cross-sectional view of an ignition coil in accordance with an embodiment of the present invention.

2 is a side view of the ignition coil according to the embodiment;

3 is a magnetization performance diagram of a non-oriented silicon steel piece.

4 is a magnetic characteristic diagram illustrating the magnetic performance of the ignition coil according to the embodiment.

5 is a characteristic diagram illustrating the relationship between the secondary voltage and the primary cut-off current of the ignition coil of the present invention having permanent magnets, as compared with the prior art without permanent magnets.

6 is a schematic diagram illustrating a basic magnetic circuit for the iron core of the prior art with permanent magnets.

7 is a performance characteristic diagram illustrating the basic magnetic performance of the ignition coil of the prior art.

8 is a performance characteristic diagram illustrating the magnetic characteristics of the ignition coil of the prior art.

FIG. 9 is an explanatory diagram for explaining a method of determining an appropriate value for the maximum working magnetic flux density of an iron core in the positive magnetic flux region of the magnetic performance characteristics shown in FIG. 8; FIG.

10 is a characteristic diagram illustrating the relationship between the permanent magnet thickness (LM) versus the voltage (V2) generated by the secondary winding and the cross-sectional area ratios SG / SF and SM / SF.

11 is a characteristic diagram illustrating the relationship between the permanent magnet thickness LM and the secondary voltage V2.

12 is a characteristic diagram illustrating the relationship between primary winding cut-off current and secondary voltage of prior art ignition coils with or without permanent magnets.

13 is a magnetic performance characteristic diagram when the cross-sectional area ratio SM / SF = 3.

14 is a magnetic performance characteristic diagram of an ignition coil having no permanent magnet.

15 is a cross-sectional view of an ignition coil having no permanent magnets.

16 is a side view of an ignition coil without a permanent magnet.

17 is a cross-sectional view of an ignition coil according to the prior art.

18 is a side view of an ignition coil according to the prior art.

* Explanation of symbols for main parts of the drawings

1: iron core 2: air gap

6: primary winding 8: secondary winding

The present invention relates to an improved ignition coil mainly used in automotive internal combustion engines.

Various types of ignition coils have been known so far, where permanent magnets are inserted in the air gap section of the iron core to increase the stored energy. In Japanese Patent Laid-Open No. 2-37705 (USP 4,990,881), an improvement of these coils is shown. 6 is a schematic diagram illustrating a basic magnetic circuit of an iron core having a permanent magnet inserted into an air gap portion of an ignition coil. In the magnetic circuit shown in FIG. 6, reference numeral SF is a cross section of an iron core in which magnetic flux Φ flows, SG is a cross section of a permanent magnet supporting the core, LF is a length of a magnetic path, and SM is a hatch ( The cross-sectional area of the hatched permanent magnet, and LM is the thickness of the permanent magnet.

7 and 8 are performance characteristic diagrams for explaining the magnetic performance of the ignition coil according to the Japanese Patent Laid-Open Publication.

Referring to FIG. 7, the primary winding is wound n times on the winding portion of the ignition coil, and generates magnetic flux (+ Φ ) in the opposite direction of the magnetization direction by the permanent magnet which generates magnetic flux (− Φ ) in the opposite direction. In order to make the excitation or primary current Ip 'flow through the primary winding, the energy stored in the primary winding is represented by the hatched area W' and is expressed by the following equation.

W '= (1/2) (2 Φ ') · nIp '= Φ ' · nIp '

In order to maximize the energy (W ') stored in the primary winding of the ignition coil with the permanent magnet inserted, the magnetization force of the permanent magnet is close to the saturation point of the magnetic flux within the core in the negative magnetic field in the lower left of FIG. Magnetize to point (P).

In FIG. 9, which is a broken line diagram of the quantum flux region, the curve (a) shows the magnetization characteristics of the iron core, the straight line (b) shows the magnetization characteristics of the permanent magnet, and the curve (c) shows the magnetization characteristics of the primary winding. Indicates. The maximum magnetic flux density of the iron core is given by a value coinciding with the linear tangent point on the curve (a) parallel to the straight line (b) which is the combined sum of (a) and (b).

Conversely, the slope of the magnetization curve of the primary winding is determined by the permeability of the permanent magnet ( μ ), so to increase the energy stored in the primary winding represented by the hatched region (W) in FIG. It is important that the permanent magnetic material having a permeability value is selected so that a permeability value close to 1 contributes to the air gap that stores the energy to incline the magnetization curve of the primary winding shown in FIG.

In relation to the ignition coil referred to in FIG. 6, the relationship between the thickness of the permanent magnet (LM) and the cross-sectional area ratio (SG / SF) of the iron core was tested. Considering the quantum flux region in FIG. 8, the magnetization force (nIp / 2) generated by the excitation current flowing through the primary winding results in the magnetization force (HF / LF) of the iron core (HF being the magnetic field in the iron core) and the permanent magnet. It is the combined force of the magnetizing force (H · LM) across the air gap. Therefore, the above described relationship is represented by the following equation. In this case, Ip is the maximum primary winding current, that is, the current under normal operation.

nIp / 2 = HF ・ LF + H ・ LM

And the following result is

H = (nIp / 2-HF ・ LF) / LM [AT / m]

In contrast, the following equation is deduced so that the magnetic flux density (MB) in the permanent magnet is expressed as

BM = μH

BM = μ (nIp / 2-HFLF) / LM

Given the BG, the magnetic flux density in the air gap containing the permanent magnets, the following relation is inferred.

BG, SG = BF, SF

As described later, when SG ≒ SM is preferably selected within the relation between the permanent magnet and the iron core of the ignition coil, the above equation is immediately converted into BM · SG = BF · SF.

Combining this equation with the direct equation of BM, the result is

BM = BF ・ SF / SG = μ ㆍ (nIp / 2-HF ・ LF) / LM

As a result, the thickness LM is represented by the following relationship.

LM = [SG / SF] · [ μ · (nIp / 2-HF ・ LF) / BF]

Therefore, this is a direct equation of the cross-sectional area ratio (SG / SF), which is further converted into the following equation.

SG / SF = 2.BF.LM / [ μ ㆍ (nIp-2HF ・ LF)] ........... (1)

In the negative magnetic flux region of the hatched region in the performance characteristic diagram of FIG. 8, the iron core needs to be magnetized by the magnetization force of the primary winding opposite to the energy of the permanent magnet, so that the quantum flux passes through the iron core. Therefore, the iron core is first magnetized to the point P close to the saturation point in the sound magnetic flux region of the iron core shown in the lower left of FIG. 8 by the magnetization force of the permanent magnet as described above. The iron core is then magnetized to a point T close to the saturation point in the quantum flux region indicated in the upper right region of FIG. 8 by the magnetizing force nIp by the exciting current Ip flowing through the primary winding. In this case, the maximum energy (EM) of the permanent magnet, which depends on the form and material of the permanent magnet, is related to the eighth in-domination energy (W) stored in the primary winding, where EM = (1/2) W. The direct area of W in FIG. 8 is W = (1/2) (2, BF, SF), nIp = BF, SF, nIp.

In contrast, the maximum energy production of a permanent magnet is expressed as (B · F) _MAX , so the theoretical value of the maximum energy (EM) of the permanent magnet is expressed as EM = (B · F) _MAX · (SM · LM). . Since the operating point of the permanent magnet is determined by the slope of the magnetization curve (b) of the permanent magnet shown in FIG. 9, the selection point is the point providing the maximum energy production (BH) _MAX or near the optimum point.

Therefore, the energy stored in the primary winding is expressed as

W = BF ・ SF ・ nIp = 2EM = 2 · (B · M) _MAX ㆍ (SM ・ LM)

From this equation, the following direct equation of the cross-sectional area ratio (SM / SF) is obtained.

SM / SF = BF ・ nIp / (2 ・ (BH) _MAX ㆍ LM) ............... (2)

Equations (1) and (2) represent the relationship between the sizes of the individual parts of the magnet circuit in the ignition coil.

SmCo5 (samarium cobalt) is used as the material of the permanent magnet and the details of the elements are as follows.

(BH) _MAX = 20 MGOe and μ = 1.05

The iron core is made of non-oriented silicon metal pieces and the values of the elements are as follows.

SF = 49 mm2, BF = 1.4 Wb / m2, nIp = 800AT,

HF = 150AT / m, LF = 0.1m

The values of the elements are substituted in equations (1) and (2) to find the relationship between the LM shown diagrammatically in FIGS. 10 and 11 and the respective area ratios SG / SF and SM / SF. Shown in FIGS. 10 and 11 are secondary voltages generated by the secondary winding, which is a performance test performed on various ignition coils with individual portions of different sizes depending on the change in the thickness (LM) of the permanent magnet. Obtained from FIG. 11 shows the distribution curve of the secondary voltage (V2) shown in FIG. 10 after the conversion to the two-dimensional characteristic curve, and the relationship between the magnitude of the secondary voltage (V2) and the thickness of the permanent magnet (LM) Shows.

Under the given ignition coil size conditions, the following relationship can be considered as a result of the data acquisition shown in FIGS. 10 and 11.

(a) The cross-sectional area of the SG 지지 SM, ie the permanent magnet support of the iron core, shall be substantially equal to that of the permanent magnet.

(b) The secondary voltage (V2) is significantly higher as long as the values of LM, SM / SF and SG / SF are in the following ranges.

0.6mm <LM <1.8mm

2 <SM / SF <6

1.5 <SG / SF <4.5

15 and 16 are cross-sectional and side views of another conventional ignition coil that does not have a permanent magnet. 17 and 18 show cross-sectional and side views of an ignition coil utilizing a permanent magnet according to the prior art (1), respectively. The ignition coils with permanent magnets are lighter (190 g) compared to the prior art (350 g) without the permanent magnets, since the ignition coils with permanent magnets can be easily understood with reference to each drawing and dimension, respectively. It is considered thoroughly.

The prior art ignition coil shown in FIG. 17 and described above maximizes the magnetic flux density and consistently drives 6 A (amps) into the primary winding with a resistance of less than 1 ohm even when the battery voltage drops below a certain value. It is most effective for very sophisticated ignition coils to supply them. The relationship between the secondary output voltage and the primary cut-off (I1-V2) of the prior art ignition coil, which does not have a permanent magnet but has the same secondary output voltage at the same primary current of 6 A, is shown in FIG. It is compared graphically with dashed lines.

The relationship I1-V2 of FIG. 12 shows that the secondary output voltage of the prior art twinning coil is mainly the same near 6A of the primary current. However, the output voltage in the form of permanent magnets is clearly smaller than not having permanent magnets, especially in the primary current range lower than 3A. As shown in FIG. 13, this means that the magnetization characteristic of the primary winding is practically curved and permanent when the ratio between the cross-sectional area SM of the permanent magnet and SF of the iron core is chosen to be 3 (SM / SF = 3). This is why the magnetization is negatively magnetized by the magnet to the magnetic saturation region. In other words, as shown in FIG. 14, the energy W3 'stored in the low current range is less than the energy W' of the ignition coil that does not have permanent magnets by an amount corresponding to magnetic saturation. This results in poor output performance.

In an ignition system with a primary winding larger than 1 ohm of the ignition coil and whose primary current is controlled primarily by the stay angle, the output performance becomes very important near the 3 A primary current range, especially at low battery voltages and high temperatures. Important for engine cranking time. Technical study and understanding of this phenomenon became the basic motivation for the inventor of the present invention.

It is an object of the present invention to newly understand a small and light ignition coil without loss of output performance in the low primary current range.

According to the present invention for solving the above object, the thickness of the permanent magnet (LM) and the ratio SM / SF between the two cross-sectional areas SM and SF are selected as follows. The working magnetization region of the primary winding should not be in the curved region of magnetization properties in the negative region as shown in FIG.

0.6 mm <LM <1.8 mm and 1.3 <SM / SF <3.0

The invention is described in more detail below with reference to the embodiments shown in FIGS. 1 to 5. 1 is a cross-sectional view of an ignition coil according to an embodiment of the present invention, and FIG. 2 is a side view of the ignition coil. In FIGS. 1 and 2, the iron core 1 is made of thin non-directional silicon metal pieces and forms a closed magnetic flux circuit through an air gap 2 arranged obliquely in the iron core 1.

The permanent magnet 4 is inserted into the air gap 2 of the iron core 1. The primary winding 6 is wound on the iron core 1. The permanent magnet 4 is magnetized in a direction opposite to the magnetization direction by the exciting current flowing through the primary winding 6. For this embodiment, the electrical resistance of the primary winding 6 is made greater than one. Another solution for making an electrical resistance greater than one is to connect an external resistor in series with the primary winding 6. Furthermore, the secondary winding 8 is wound over the primary winding 6. The correlation between the thickness LM of the permanent magnet 4 in the winding part, the oblique cross-sectional area SM of the permanent magnet and the non-slanted planar cross-sectional area SF of the iron core 1 is selected to satisfy the following conditions. Besides this condition, the oblique cross-sectional area SG of the iron core in the air gap part should be made almost equal to the cross-sectional area SM of the permanent magnet 4.

0.6mm <LM <1.8mm

1.3 <SM / SF <3.0

Here, referring to the relationship between the magnetization force H and the magnetic flux density B on the BH characteristic curve of the non-oriented silicon metal piece shown in FIG. 3, the increase in the magnetization force H is 1 [1]. It increases from the point T]. In other words, the magnetic flux density B starts to saturate beyond the point B = 1 [T], and thus the stored energy does not increase because the magnetic energy is the integral product of the magnetization forces H by the magnetic flux density B.

Therefore, as shown in Fig. 4, it is possible to control the magnetization curve to the curve part in the negative magnetization region on the lower left side of the drawing as the primary curve. The magnetic saturation point of the iron core 1 generally characterizes the magnetic working range up to 1.5 [T] on the magnetization curve of the iron core 1 in the positive region since the BF is almost equal to 1.5 [T], and negative It is good practice to characterize the magnetic working point of the permanent magnet biased by 2/3 of the saturation point.

In the lower left side of FIG. 4, the magnetization by the primary winding in the negative region is not a magnetic saturation region. The extremely small bias of the permanent magnet has the opposite effect on the aim of minimizing the ignition coil. In particular, when the thickness LM of the permanent magnet 4 is the same as that of the prior art, the cross-sectional area SM of the permanent magnet is 2/3 of the cross-sectional area of the permanent magnet applied in the prior art. In the embodiment of the present invention, as the permanent magnet, a magnetic material such as the above-mentioned prior art having a specification of mu = 1.05 and (BH) _MAX = 20MG.Oe is used.

The thickness LM of the permanent magnet 4 of the present invention is selected within the same range as the prior art (0.6 mm < LM < 1.8 mm). This is because this range provides the maximum secondary voltage V2 as shown in FIG. In addition, the cross-sectional area ratio SM / SF is selected within the range of 1.3 <SM / SF <3.0 in the following relationship. That is, if the condition SG = SM is added to the 1.5 <SG / SF <4, 5, and 2 <SM / SF <6 relationships in the prior art, the relationship between SM and SF falls within the following limitations.

2 <SM / SF <4.5

In an embodiment of the present invention a new condition, which is two thirds of the elements described in detail, must be added to the condition, which results in the following minimum and maximum limits of the allowable SM / SF ratio.

1.3 <SM / SF <3.0

As shown in FIG. 4, the ignition coil of the present invention uses a straight portion as a magnetization curve for the primary winding with the introduction of a 2/3 element and an SM / SF ratio of 1.5. Moreover, as shown in FIG. 14 in relation to the prior art, the energy W ' _1.5 stored on the low current range is approximately equal to the energy W' of the ignition coil without permanent magnets. 5 shows no difference between the ignition coil of the present invention and the cut-off current of the primary winding 6 of the prior art without permanent magnets versus the secondary output voltage V2. As can be clearly understood with reference to the dimensions of the ignition coil of the present invention provided for easy understanding in FIGS. 1 and 2 compared to FIGS. It can be understood by comparison of the weight 350 g of the prior art without degrading the output performance.

The present invention should not be limited to the above-described specification, but may be modified in various ways without departing from the spirit and spirit of the invention.

Claims (10)

The ignition coil comprises an iron core 1 forming a closed magnetic path through an air gap 2 provided in the iron core; A primary winding wound on the iron core to magnetize the iron core when an electrical current is supplied, the primary winding having a primary resistance greater than one; A secondary winding 8 wound around the iron core; And a permanent magnet (4) magnetized in a direction opposite to the magnetization direction by the supply of electrical current to the primary coil, and inserted into the air gap of the iron core, the cross-sectional area SG of the iron core into which the permanent magnet is inserted. Is substantially the same as the cross-sectional area (SM) of the permanent magnet, the thickness (LM) of the permanent magnet is in the range of 0.6mm to 1.8mm, the cross-sectional area (SF) and the iron core (SM) of the iron core wound winding Ignition coil, characterized in that the ratio (SM / SF) between the cross-sectional areas of The ignition coil of claim 1 wherein the ignition coil is used in an internal combustion engine of an automobile. The method of claim 2, wherein in the magnetic permeability (μ) of the permanent magnet is substantially 1, said permanent magnet includes samarium and cobalt, and the iron core is in the ignition coil is characterized by comprising a non-directional silicon metal piece. 3. The method of claim 2, wherein the primary coil is connected to an external resistor providing the primary resistance to the primary coil, and magnetization in the opposite direction by the permanent magnet is limited to 1.0 [T]. Ignition coil. 2. The magnetization of claim 1, wherein the magnetization in the opposite direction by the permanent magnet in the negative region is equal to two-thirds of the magnetization force that magnetizes the iron core in the positive region to a maximum value of the electrical current generally flowing through the primary coil. An ignition coil characterized by the same practically. The ignition coil comprises an iron core 1 forming a closed magnetic path through an air gap 2 provided in the iron core; A primary winding 6 wound on the iron core to magnetize the iron core when electrical current is supplied; A secondary winding 8 wound around the iron core; And a permanent magnet (4) magnetized in a direction opposite to the magnetization direction by the supply of electrical current to the primary coil, and inserted into the air gap of the iron core, wherein the cross-sectional area of the iron core into which the permanent magnet is inserted (SG). ) Is made substantially the same as the cross-sectional area (SM) of the permanent magnet, the thickness of the permanent magnet (LM) is in the range of 0.6mm to 1.8mm, the cross-sectional area (SF) and the iron core ( Ignition coil, characterized in that the ratio (SM / SF) between the cross-sectional areas of the SM) is in the range of 1.3 to 2.0. 7. The ignition coil of claim 6 wherein said ignition coil is used in an internal combustion engine of a motor vehicle. The method of claim 7, wherein in the magnetic permeability (μ) of the permanent magnet is substantially 1, said permanent magnet includes samarium and cobalt, and the iron core is in the ignition coil is characterized by comprising a non-directional silicon metal piece. 8. The ignition coil of claim 7, wherein the primary coil is connected to an external resistor providing the primary resistance to the primary coil. 10. The magnetization of claim 9 wherein the magnetization in the opposite direction by the permanent magnet is limited to 1.0 [T], and the magnetization in the opposite direction by the permanent magnet in the negative region generally refers to the iron core in the positive region. An ignition coil characterized by substantially equal to two-thirds of the magnetizing force that magnetizes the secondary coil to the maximum value of the electrical current flowing through it.