JPH0124911Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to an improvement of an ignition coil for a magneto-powered internal combustion engine used for ignition of an internal combustion engine.

Conventional technology Due to its nature, magneto-type ignition circuits for internal combustion engines overheat the transistors in the transistor circuit with reverse current due to the increase in back electromotive force generated in the primary winding as the rotational speed of the internal combustion engine increases. In addition to deteriorating the secondary winding, the secondary back electromotive force generated in the secondary winding increases, and the resulting voltage causes discharge to occur in the spark plug, causing ignition to occur earlier than the normal ignition timing (pre-ignition). It has the problem of causing problems.

As a conventional measure to prevent this, there is a circuit in which a diode is inserted and connected between both terminals of the primary winding to allow a reverse current to flow in a short-circuited state.

According to this circuit, characteristic deterioration and premature ignition of the transistor in the transistor circuit described above can be completely prevented, but since the reverse current flows in a short-circuited state, as the rotation speed increases, the reverse current and the resulting positive current increase. Since the reverse magnetomotive force increases, the generation of the positive current following the reverse current is delayed, resulting in a delay in establishing the cutoff control voltage for the positive current flowing through the transistor, that is, a delay in the ignition timing, A defect occurs in that the output of the internal combustion engine decreases in the high rotational speed region.

In order to eliminate this defect, there are circuits that limit the reverse current by inserting and connecting a series circuit of a diode and a resistor or a series circuit of a diode and a constant voltage diode between both terminals of the primary winding. Resistors have the disadvantage of overheating and burning out, and large-capacity ones are large and take up too much storage space.
Also, in the latter case, low-voltage diodes with small capacity will overheat and explode, and large-capacity diodes will be expensive and large, taking up too much storage space, and the tolerance of Zener voltage is large, and if the selection is incorrect, the transistor There is a risk that reverse current may flow into the circuit's transistors.

In addition, in these cases, the above diode,
It is difficult to integrate each element such as a resistor with the coil side due to the size and number of elements, so they are often connected to the transistor circuit side, which allows heat sources such as diodes and resistors to be connected to the transistor circuit. Therefore, a design that takes heat dissipation into consideration in the high rotational speed region is required, and the transistor circuit side is housed in a metal case or the like.

Furthermore, this ignition circuit section is easily overheated for the above-mentioned reasons, and since it is attached to an internal combustion engine, it must be able to withstand strong vibrations, and the diode D is used to prevent the intrusion of rainwater, etc. If the ignition coil T and the ignition coil T were integrally molded with the synthetic resin of the external body, it would be difficult for the heat to escape to the outside, and there was a risk of further overheating due to the reverse current.

Problems to be Solved by the Invention The invention introduces a reverse current between both ends of the primary winding of an ignition coil, which is made up of a U-shaped iron core that constitutes a conventional magneto power source and has primary and secondary windings wound around it. The purpose of this invention is to solve the above-mentioned problems in ignition coils with reverse current processing circuits in which diodes are connected in the direction of flow, that is, delays in ignition timing, and to prevent a decrease in the output of an internal combustion engine due to this. .

Another purpose is to improve the vibration resistance and water resistance of the ignition coil, and to improve the vibration resistance and water resistance of the ignition coil.
The aim is to reduce heat generation due to reverse current such as _T1 .

Another purpose is to facilitate and ensure the connection between the ignition coil and the transistor circuit.

Means for Solving the Problems As shown in Fig. 4, the present invention involves winding a primary winding T ₁ and a secondary winding T ₂ around a substantially U-shaped _core F. , _F2 , an ignition coil for a magneto-powered internal combustion engine is provided with a freely rotatable rotor 18 containing a built-in magnet, and an intermediate lead wire 3 is connected to the primary winding _T1 as shown in FIG. established,
A diode D is connected between this intermediate lead wire 3 and one end of the primary winding T ₁ in a direction that conducts the reverse current I generated in the primary winding T ₁ .

Furthermore, as shown in FIGS. 1 and 2, the diode D is disposed at one end of the ignition coil, and the primary winding _T1 , the secondary winding _T2 , and the diode D are integrated with a synthetic resin outer body 17. The lead wire 15 of the primary winding _T1 is exposed outside the synthetic resin outer body 17.

Operation With the above configuration, the reverse current I generated between some of the windings of the primary winding _T1 flows through the diode D, and the inflow of reverse current into the transistor circuit 19 is restricted, and the transistor circuit In addition to preventing the No. 19 transistor Q from overheating due to reverse current and deteriorating its characteristics, it also suppresses the increase in secondary back electromotive force that causes premature ignition in the medium and high rotational speed range, and prevents premature ignition. prevent.

Moreover, the value of the above-mentioned reverse current I becomes considerably lower than the reverse current flowing through both ends of the primary winding when both terminals of the primary winding _T1 are short-circuited with a diode,
Therefore, the delay in establishing the forward current I ₉ of the primary winding T ₁ in the range of medium to high rotational speeds is extremely reduced, and the heat generated therefrom is also reduced.

Embodiment To explain the present invention in detail with reference to the attached drawings of the embodiment, as shown in FIGS. 1 to 4, a thick wire primary winding T ₁ is wound in several layers around a bobbin 1 having a square center hole. Immediately above this, a secondary winding T ₂ of ultra-fine wire is wound in several tens of layers while inserting insulating paper or the like between each layer to provide interlayer insulation. In this case, the winding start wire ₂ , intermediate leader wire 3 at the layer end, and winding end wire 4 of the primary winding T1 are all drawn out to the outside of the bobbin ₁ in advance, and the winding start wire of the secondary winding T2 ( (not shown) is connected to the vicinity of the end winding wire 4 of the primary winding _T1 , and the end winding wire 5 is drawn out in advance from approximately the center of its outer periphery.

The iron core F consists of a core L-shaped part F ₁ and an iron core I-shaped part F ₂ , each of which has a mounting hole for fixing the core F so as to maintain a small gap between it and the rotor 18 fastened to the rotating shaft of the internal combustion engine. 6a, 6b, iron core L
A ground plate 7 is fastened to one surface of the rectangular straight portion of the character portion _F1 along this side with a rivet 8. The rectangular straight part of the L-shaped part _F1 of the iron core has the above-mentioned primary winding.
The L-shaped part of the iron core after inserting the bobbin 1 wound with T ₁ and the secondary winding T ₂ and the support plate 9 having a square center hole.
Insert the iron core I-shaped portion F ₂ into F ₁ using the dovetail 10 .

The support plate 9 is an insulating plate molded from synthetic resin into which the diode D is inserted and a primary terminal plate 11 and a secondary terminal plate 12 are molded and enclosed.

In the above configuration, the winding start wire 2 of the primary winding T ₁ is connected to the bent portion 7a at one end of the ground plate; the intermediate lead wire 3 at the layer end of the primary winding T ₁ is the anode wire of the diode D on the support plate 9. 13; the winding end wire 4 of the primary winding T ₁ is connected to the primary terminal plate 11 on the support plate 9; the winding end wire 5 of the secondary winding T ₂ is connected to the secondary terminal plate 12 on the support plate 9; the diode The cathode wires 14 of D are connected to the peaks 7b at the other end of the ground plate 7 by soldering (not shown), and the primary terminal board 11 has lead wires 15 connected to the transistor circuit 19; High-voltage cords 16 connected to spark plugs are connected to the next terminal plates 12 by soldering (not shown).

Note that the diode D has its anode wire 13 connected to the winding end wire 4 of the primary winding T ₁ via the primary terminal plate 11, and its cathode wire 14 connected to the intermediate lead wire 3 of the primary winding T ₁ . Also good.

As mentioned above, the diode D is fitted onto the insulating support plate 9, and is connected directly between some windings of the primary winding _T1 at the shortest distance, and finally connected to the synthetic resin of the outer body 17. is solidified.

With the above configuration, the reverse current I generated between some of the windings of the primary winding _T1 flows through the diode D, suppressing the flow of reverse current into the transistor circuit, and suppressing the flow of the reverse current into the transistor circuit. Q
In addition to preventing overheating caused by reverse current and deterioration of its characteristics, a diode D is installed in a part of the primary winding _T1 to prevent an increase in the secondary back electromotive force that causes premature ignition in the medium and high rotational speed range. By passing a reverse current I through the ignition current I, pre-ignition can be prevented.

Furthermore, the reverse current I flowing through the primary winding T ₁ is considerably smaller than the reverse current flowing when both ends of the primary winding T ₁ are short-circuited with a diode. primary winding in
The delay in establishing the forward current I at _T1 is also extremely reduced, making it possible to maintain proper ignition timing over the entire rotational speed range.

Furthermore, the primary winding T ₁ , the secondary winding T ₂ and the diode D are integrally molded into a synthetic resin outer body 17 , and the diode D is connected to the intermediate lead wire 3 of the primary winding T ₁ and one end thereof. In addition to reducing heat generation due to reverse current of things inside the synthetic resin outer body 17 by connecting them, the connecting portion of the anode wire 13 and cathode wire 14 can be made sufficiently resistant to strong vibrations of an internal combustion engine. As well as being able to
Water resistance can also be increased.

Furthermore, a primary winding T ₁ is placed outside the synthetic resin outer body 17.
Since the lead wire 15 of the ignition coil part 2 is exposed,
Connection with the zero transistor circuit section 19 can be made with a single lead wire 15 by connecting the ground of both circuit sections to the case plate of the internal combustion engine as a common ground. The risk of wire breaks, generation of noise sources, and deterioration of electrical insulation can be reduced.

In addition, since the diode, which is a heat source, is removed from the transistor circuit, there is no need to design with heat dissipation in mind, making the design of the transistor circuit much easier, and the housing case for the transistor circuit can also be made of plastic instead of metal. As a result, the transistor circuit section can be miniaturized, and the entire ignition device can also be miniaturized.

Effects of the Device As explained above, the device of the present invention connects a diode between the intermediate lead wire of the primary winding and one end thereof in a direction that conducts the reverse current generated in the primary winding. It is possible to prevent deterioration of the internal combustion engine and maintain appropriate ignition timing at all times over the entire rotational speed range of the internal combustion engine.

Further, by integrally constructing the diode and the ignition coil with a synthetic resin outer body, the connection between the ignition coil part and the transistor circuit part can be made easy and reliable, and vibration resistance and water resistance can be improved.

Furthermore, in addition to reducing the heat generated by the primary winding and the diode, the diode, which is the heat source, is separated from the transistor circuit, making it easier to design the transistor circuit, and the housing case for the transistor circuit can be changed from metal to plastic. In addition, the transistor circuit can be made smaller, and the ignition device can be made smaller.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a main part of an embodiment of the present invention, Fig. 2 is a sectional view taken along the - line in Fig. 1, Fig. 3 is a sectional view taken along the - line in Fig. 1, and Fig. 4 is a sectional view taken along the - line in Fig. 1. FIG. 1 is a sectional view of a main part showing the relationship between the rotor and the rotor, and FIG. 5 is a schematic diagram of the main part showing a circuit diagram and a connection point between an ignition coil section and a transistor circuit section. F...Iron core, _F1 ...L-shaped part of the iron core, F2 _... I-shaped part of the iron core, T...Ignition coil, _T1 ...Primary winding, _T2 ...Secondary winding, I...Reverse Current, I ₀ ... Forward current, D ... Diode, Q ... Transistor, 1
...Bobbin, 2...Start line of primary winding T ₁ , 3
...Intermediate lead wire of primary winding _T1 , 4...Primary winding
Winding end line of T ₁ , 5... Winding end line of secondary winding T ₂ ,
6a, 6b...Mounting hole, 7...Ground plate, 7a...
...Folded portion of ground plate 7, 7b...Ground plate 7
apex, 8... rivet, 9... support plate, 10...
... Ant, 11 ... Primary terminal board, 12 ... Secondary terminal board, 13 ... Anode wire, 14 ... Cathode wire,
15...Primary lead wire, 16...Secondary high voltage cord, 17...Synthetic resin outer body, 18...Rotor magnet, 19...Transistor circuit section, 20
...Ignition coil section.

Claims (1)

[Scope of utility model registration request] An intermediate lead wire 3 is provided on the primary winding T ₁ of the ignition coil T, which is formed by winding a primary winding T ₁ and a secondary winding T ₂ around a U-shaped iron core F constituting a magneto power source. Between the wire 3 and one end of the primary winding T ₁ ,
A diode D is connected in a direction that conducts the reverse current I generated in the primary winding _T1 , and the diode D and the ignition coil T are integrally molded into a synthetic resin outer body 17, and the synthetic resin outer body Outside of 17,
An ignition coil for a magneto-powered internal combustion engine in which the lead wire 15 of the primary winding _T1 is exposed.