JPH02228009A - Ignition transformer - Google Patents

Abstract

PURPOSE:To make the entire constitution compact by providing a pair of bias magnets which impart magnetic biases to the magnetic flux which is generated in a magnetic circuit. CONSTITUTION:An ignition transformer 1 has an approximately cylindrical shape and has the following parts: a case 2 wherein an ignition-plug mounting part 2a is provided at one end part, and the other end part is opened; a post shaped core 3]; a secondary winding 4 which is wound around the outer surface of the core 3; a primary winding 5 which is wound around the outer surface of the winding 4; an outer core 6 which is arranged around the outer surface of the primary winding 5; and bias magnets 7a and 7b which are arranged at both end parts of the core 3. A bobbin 8 is formed in a length so that the bobbin is made to extrude sideward from both ends of the core 3. The bias magnets 7a and 7b are attached to the insides of both ends of the bobbin so that the magnets are in close contact with the core 3. A connector 59 is supported by a supporting member 9 that is fixed to the end part on the side of the bias magnet 7a under the state wherein the connector is located at the opening of the ignition-plug mounting part 2a. Thus the B-H hysteresis characteristic is improved, and the entire constitution is made compact.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an ignition transformer, and more particularly to an ignition transformer that supplies high voltage to spark plugs of various internal combustion engines.

(Prior Art) A conventional example of this type of ignition transformer will be explained with reference to FIGS. 5 and 6.

In the ignition transformer 50 shown in the figure, 51
．． 52 is a core made of a magnetic material such as a silicon steel plate, 53 is a primary winding for low voltage input, 54 is a secondary winding for high voltage output, and 55 is an insulating cover that covers the entire body.

Furthermore, 56 is a bobbin around which the primary winding 53 is wound, and 57 is a bobbin around which the secondary winding 54 is wound.

Incidentally, in FIG. 5, 58 is a spark plug attached to a connector 59 provided in the ignition transformer 50.

The bobbin 7 has winding portions partitioned along the axial direction by collar portions 71 provided at appropriate intervals, and the secondary winding 54 is continuously wound around each winding portion.

Then, the inner diameter hole 7 of the bobbin 57 around which the secondary winding 54 is wound
2, the bobbin 56 with the -th order winding 53 wound thereon is coaxially inserted and arranged, and the bobbin 56 passes through the inner diameter hole 61,
Two cores 51 and 52 are joined from both sides in the axial direction so as to butt each other.

As drive circuit systems for the ignition transformer 50 described above, a capacitor, discharge, ignition system (hereinafter referred to as CD1 system) and a full transistor system that utilizes the flyback energy of the ignition transformer 50 are well known. FIG. 7 shows a full transistor drive circuit, in which a transistor 80 serving as a switching element is inserted and connected in series with the secondary winding 53, and a pulse signal P is supplied to the base of this transistor 80 to perform a switching operation. It looks like this.

The polarities of the secondary winding 53 and the secondary winding 54 are determined so that when the transistor 80 is turned off, a high voltage pulse is generated in the secondary winding 54 due to flyback energy release.

The excitation energy stored in the transformer 50 when the transistor 80 is turned on is converted into flyback energy when the transistor 80 is turned off next time.
The signal is output from the secondary winding 54 and supplied to the ignition plug 58, causing the ignition plug 58 to generate a spark discharge. FIG. 8 is a waveform diagram of the high voltage pulse taken out to the high voltage output coil 54.

(Problems to be Solved by the Invention) However, in the case of the above-described ignition transformer 50, a low DC voltage is supplied to the negative secondary winding 53, and a DC excitation current is caused to flow through the primary winding 53. Therefore, the cores 51 and 52 are always biased in one direction, that is, in the characteristic region A1 belonging to the first quadrant in the B-H hysteresis characteristic shown in FIG. The same applies when the CDI method is adopted.

As a result, the utilization efficiency of the cores 51, 52 is poor, and it is difficult to reduce the size of the cores 51, 52 when trying to maintain the high voltage output from the secondary winding 54 above a certain level. be.

This type of ignition transformer 50 is placed in a predetermined position of an internal combustion engine with limited installation space, and miniaturization is an extremely urgent requirement, and the conventional ignition transformer 50 cannot meet this requirement. I can't respond fully.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an ignition transformer whose overall structure can be made smaller.

[Structure of the Invention] (Means for Solving the Problems) The present invention includes a primary winding for low voltage input, a secondary winding for high voltage generation, and a core for magnetically coupling the two windings. The ignition transformer is provided with a magnetic circuit that supplies a high voltage induced in the secondary winding to the spark plug, the ignition transformer comprising a pair of magnetic circuits that apply a magnetic bias to the magnetic flux generated in the magnetic circuit at both ends of the core. It is equipped with a bias magnet.

(Function) The function of the ignition transformer having the above configuration will be explained below.

By providing a pair of bias magnets at both ends of the core, the B-H hysteresis characteristic of this ignition transformer is improved, and the core can be made smaller than in the conventional example.

(Example) An embodiment of the present invention will be described below with reference to FIG.

The ignition transformer 1 shown in the figure is approximately cylindrical,
A case 2 with a spark plug mounting part 2a at one end and an open end, a straight columnar core 3 built into the case 2, and a core 3 wrapped around the outer periphery of the core 3. A secondary winding 4 made of a relatively thin wire, a primary winding 5 made of a relatively thick wire wrapped around the outer periphery of the secondary winding 4, and an external core arranged around the outer periphery of the secondary winding 5. 6 and the core 3
It has bias magnets 7 a and N 7 b arranged at both ends of.

The core 3 is disposed at the center of the shield case 2 along its length, and a cylindrical first bobbin 8 is attached to the outer periphery of the core 3.

The first bobbin 8 is formed to have a length that projects laterally from both ends of the core 3, and bias magnets 7a and 7b are attached inside each end thereof in close contact with the core 3.

Further, a support member 9 made of an insulator is fixed to the end of the bobbin 8 on the bias magnet 7a side, and this support member 9 supports the connector 59 so as to face the opening of the spark plug mounting portion 2a. It has become.

The secondary winding 4 is wound around the outer periphery of the bobbin 8, with each layer being insulated by interlayer insulating paper (kraft paper, presspod, etc.) 10.

Furthermore, the secondary winding 5 is wound around the outer periphery of the outermost interlayer insulating paper 10, and a silicon steel plate with a thickness of about 0.1 to 0.3 vm is placed around the outer periphery of the secondary winding 5 as a core. A triple or quadruple wound cylindrical core 6 having a cross-sectional area approximately equal to the cross-sectional area of 3 is disposed. In FIG. 1, reference numeral 15 indicates a synthetic resin filler filled in the shield case 2.

Here, in the ignition transformer 1 of this embodiment, the magnetic flux φm passing through the core 3 constituting the open magnetic path type magnetic circuit is
The relationship between this and the magnetic flux φS caused by the bias magnets 7a and 7b will be mentioned.

When a low voltage is applied to the secondary winding 5 by the same means as in the conventional example and a direct current is passed through the secondary winding 5, the direction of the magnetic flux φm passing through the core 3 is the direction of the arrow shown in FIG. Then,
The magnetic flux φS caused by the bias magnet 7a N7b is the first
As shown in the figure, in a direction opposite to the magnetic flux φm,
The magnetic poles of both bias magnets 7a and 7b are arranged.

By arranging the magnetic poles of the bias magnets 7as7b in this manner, the B-H hysteresis characteristic of the core 3 in the ignition transformer 1 is shifted to the upper side of the first quadrant than in the conventional example, as shown in FIG. Ao, as in the characteristic region, that is, the magnetic bias ΔB by both bias magnets 7a17b is applied, and as a result,
The operating range of the core 3 can be expanded by approximately 30%.

Regarding the materials of the core 3 and the bias magnets 7a and 7b described above, when the ignition transformer 1 is used at a low frequency for the spark plug 58 as in this embodiment, the core 3 is
As a bias magnet 7a, 71), a metallic magnetic material with a large bias effect, such as silicon steel or permalloy, is used.
A rare earth magnet such as samarium cobalt or neodymium iron may be used as the magnet.

Further, when the ignition transformer 1 is used at a high frequency such as a flyback transformer for a television, a ferrite-based magnetic material with low high-frequency loss may be used as the core 3, and a ferrite-based magnet may be used as the bias magnet.

According to the above-described ignition transformer 1, the open magnetic path type core 3 is used, and the core 3 is provided at both ends of the core 3.
By providing bias magnets 7a and 7b that apply a reverse magnetic bias to the magnetic flux φm passing through, the B-H hysteresis characteristic of the core 3 is improved, the space occupied by the core 3 itself is reduced, and the ignition transformer 1 is made smaller. It becomes possible to aim for.

Next, the other side of the embodiment of the present invention will be explained with reference to FIG.

In the ignition transformer IA shown in the figure, parts having the same functions as those shown in FIG. 1 are denoted by the same reference numerals.

This ignition transformer IA is different from the flyback transformer 1 shown in FIG. The flange bobbin 11 is attached to the outer periphery of the bobbin 8, the primary winding 14 is wound around each winding portion of the flange bobbin 11, and the secondary winding 14 and the secondary winding 5 are interlayer insulated. It was insulated by paper 10'.

This ignition transformer IA can also exhibit the same functions and effects as the ignition transformer 1 described above.

The present invention is not limited to the embodiments described above (various modifications can be made within the scope of the invention).

[Effects of the Invention] According to the present invention described in detail above, it is possible to provide an ignition transformer in which the B-H hysteresis characteristic is improved by providing bias magnets at both ends of the core, and the overall configuration can be miniaturized.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an embodiment of the ignition transformer of the present invention, FIG. 2 is a cross-sectional view showing the other side of the embodiment of the present invention, and FIG. 3 is a B-H hysteresis diagram between the present embodiment and the conventional example. Comparative characteristic diagram of characteristics, Figure 4 is a characteristic diagram showing B-H hysteresis characteristics of a conventional example, Figure 5 is a cross-sectional view of a conventional ignition transformer, Figure 6 is a cross-sectional view of the same as above taken from another angle,
FIG. 7 is a circuit diagram showing an equivalent circuit and drive circuit of the ignition transformer, and FIG. 8 is a waveform diagram of high voltage pulses obtained by the ignition transformer. 1...Ignition transformer, 3...Core, 4...
...Secondary winding, 6...-Secondary winding, 7a, 7b...
・Bias magnet. Diagram

Claims (1)

[Claims] It has a primary winding for low voltage input, a secondary winding for high voltage generation, and a core that magnetically couples both of the windings, and the high voltage induced in the secondary winding is applied to the spark plug. An ignition transformer to be supplied, characterized in that a pair of bias magnets are provided at both ends of the core to apply a magnetic bias to the magnetic flux generated in the magnetic circuit.