JPS624693Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a non-contact ignition circuit for an internal combustion engine, and in particular, the primary short-circuit current flowing in the primary winding of the ignition coil is passed through a power transistor, and the conduction and interruption of the power transistor is optically switched. It is characterized in that it is controlled by means.

Conventionally, an ignition circuit for an internal combustion engine has been known in which the primary short-circuit current of the ignition primary winding is switched on and off using a mechanical contact connected in parallel with an arc-extinguishing capacitor, depending on the rotational movement of the engine's crankshaft. It is being

However, such ignition circuits have problems in that it is difficult to set the mounting positions of mechanical contacts and intermittent control cams in order to obtain the appropriate ignition timing, and that the contacts are subject to significant wear, resulting in poor durability. .

Furthermore, there is a structural limit to reducing the overall shape, and assembly requires many complicated steps. On the other hand, in response to this, the voltage induced by the power supply winding is stored in a capacitor, and this stored charge is discharged to the primary winding of the ignition coil using a transistor or a silicon control element. The primary short-circuit current induced in the primary winding of the ignition coil by the rotation of the rotor is passed through the power transistor, and the power transistor is turned on and off by the trigger of the silicon control element. There have been proposed devices in which the trigger control of the device is performed by a resistive shunt circuit for the induced current flowing through the primary winding.

However, in the former ignition circuit, the silicon control element, trigger coil, etc. can be miniaturized without any restrictions on the installation location, and while the effects of no wear on the contacts and a delay in the life of the circuit are achieved,
There was a risk that the weight would increase and the power supply windings would melt due to surge voltage.

In addition, the latter ignition circuit is a sub-switch system using a thyristor and small-signal transistor, and the high trigger level of the thyristor results in poor response sensitivity, which causes the inconvenience of not being able to ignite at low speeds. .

In contrast, the present applicant has conventionally controlled conduction and cutoff of the primary short-circuit current flowing in the primary winding of the ignition coil through a power transistor, and executed this control operation by the switching operation of a photoelectric conversion element. The switching operation is performed by a light shielding means that blocks and emits light to a light receiving element in synchronization with engine rotation, and provides a non-contact ignition circuit for an internal combustion engine that has a compact and simple configuration and does not wear out the contacts. are doing.
First, this will be explained with reference to FIG.

1 is an ignition coil, and a primary winding 1a and a secondary winding 1b are connected to each other via an iron core 1c as shown in the figure. One of these terminals is connected to a common ground. Also, the secondary winding
A spark plug 2 is connected between both terminals of 1b. A diode 3 for preventing backflow is connected in parallel to both ends of the primary winding 1a, and a collector and an emitter of a power transistor 4 are respectively connected. Further, a voltage dividing circuit (or voltage detection circuit) consisting of a voltage setting resistor 5 and a light receiving element 6 is connected to both ends of the primary winding 1a, and the power transistor 4 is connected to the midpoint P of these connections. Base is connected. In addition, in front of the light receiving element 6, a light shielding plate 7 attached to a member such as a cooking rod that rotates or moves up and down in synchronization with the rotation of the engine is arranged, and the light shielding plate 7 corresponds to the through hole 17a bored in the light shielding plate 7. Light receiving elements such as LEDs and natural light projecting means 8 are arranged as shown in FIG. In this case, the light emitting element is lit by a DC power source different from the ignition circuit.

First, due to the rotation of the rotor, a primary short-circuit current is induced in the primary winding 1a of the ignition coil 1, and this short-circuit current I is divided into the above two circuits connected in parallel as _I0 and _I1 . Ru. The waveform of the current flowing through the primary winding 1a at this time is shown in FIG. 2a. In this state, the power transistor 4 is in an ON state, and the light receiving element 6 has a high resistance, that is, it is not receiving light from the light projecting means 8. Therefore, the light receiving element 6 and the light projecting element 8 are shielded from light by a light shielding plate that rotates in synchronization with the rotation of the engine. In such a state, the internal resistance of the light receiving element 6 with respect to the resistor 5 is large, and a current flows between the base and emitter of the power transistor 4, turning on the transistor 4 and shorting the primary winding 1a. Supplies primary short-circuit current to

On the other hand, when the light-shielding plate 7 further rotates and the through hole 7a provided therein faces the light-receiving element 6, the light from the light projecting means 8 enters the light-receiving element 6, and its internal resistance is greatly reduced. . Therefore, current flows through this light receiving element 6. The current between the base and emitter of the power transistor 4 is as shown in FIG. 2b. Further, the time Δt during which this current flows is selected by arbitrarily setting the length of the through hole provided in the light shielding plate 7. Then, during this △t time, the power transistor 4 is OFF.
As a result, as shown in FIG. 2c, the current flowing up to the peak value of Ip is instantaneously interrupted. Thus, due to the cutoff operation of the power transistor 4, a high voltage is induced in the secondary winding 1b of the ignition coil 1.

By the way, in such a non-contact ignition circuit, when natural light is used as the light emitting means to eliminate energy loss in the light emitting means, there is a certain limit to the sensitivity of the light receiving element used as the light receiving means, so the amount of natural light is When the brightness decreases, the light-receiving element becomes inoperable, which makes ignition of the internal combustion engine unstable or impossible, making it impossible to use natural light as a means of projecting light. .

In order to solve such drawbacks and minimize energy loss in the light projecting means, the present invention provides separate light projecting means using natural light and light emitting elements, and when the amount and brightness of natural light decreases, the light emitting elements are automatically activated. The present invention provides a non-contact ignition circuit for an internal combustion engine, which performs stable control of a main switching circuit using a light reception signal of a sub-switching circuit.

Embodiments of the present invention will be described below with reference to the drawings. Note that the same components as those shown in FIG. 1 are given the same reference numerals.

In Figure 3, 9 is the ignition coil 1
This is a transistor that switches in synchronization with the primary short-circuit current. Its base is connected to the ground circuit of the ignition coil 1 via an input resistor 10, and its emitter is connected to the ground circuit of the ignition coil 1.
connected to the negative side circuit of Further, a resistor 1 is connected between the collector and emitter of the transistor 9.
1. A battery 12, a light receiving element 13 such as a phototransistor, and a resistor 14 are connected as shown in the figure.
A base of a control transistor 15 is connected to a midpoint between the light receiving element 13 and the resistor 14 . Further, a light emitting element 16 is connected between the collector of the transistor 15 and the emitter of the transistor 9, and the emitter of the transistor 15 is connected to the battery and the emitter of the light receiving element 13, respectively. 17, 18, 19
are optical fibers, one end of which is connected to the optical fiber connector 20, the other end of the optical fiber 17 is connected to the light emitting element 16, the other end of the optical fiber 18 is connected to the outside of the vehicle, and the other end of the optical fiber 19 is connected to the light shielding plate. It looks into the light receiving element 6 through the through hole 7a of 7.

The non-contact ignition circuit having such a configuration not only performs the same engine ignition operation as described with reference to FIGS. 1 and 2, but also performs the following switching operation of the power transistor 4.

First, the primary short-circuit current of the ignition coil 1 is passed between the collector and emitter of the power transistor 4, and when the current reaches around the peak value,
By projecting light onto the light receiving element 6 for a time Δt from the through hole 7a of the light shielding plate 7, which rotates or moves in synchronization with the rotation of the engine, and bringing the impedance of the light receiving element 6 close to zero, the power transistor 4 is is cut off, a high voltage is generated in the secondary coil 1b of the ignition coil 1, and the spark plug 2 is turned off.
generate a spark.

Incidentally, to project light from the through hole 7a of the light shielding plate 7 for a period of time Δt, natural light may be used or the light emitting element 16 may be used.

First, during bright hours such as during the day, sufficient natural light can be supplied to the light receiving element 6 from the optical fiber 18, one end of which is exposed outside the vehicle, via the optical fiber connector 20 and the optical fiber 19. Therefore, the power transistor 4 is controlled by switching with respect to the pulsed incident light input to the light receiving element 6, and an ignition voltage can be induced in the ignition coil 1 in synchronization with engine rotation.

On the other hand, when the amount and brightness of natural light decreases,
The light-receiving element 6 cannot respond to the natural light, and the light-receiving element 13 in the light projecting means 8, which has substantially the same performance as the light-receiving element 6, also has a high impedance. When a primary short-circuit current is generated here, the transistor 9 turns on in response, and the battery 1
Voltage 2 is applied to the base of control transistor 15 via resistors 11 and 14, transistor 15 is turned on, and current flows to light emitting element 16, causing it to light up. Therefore, when the amount and brightness of natural light decreases, light is emitted from the light emitting element 16 to the light receiving element 6 through the through hole 7a of the light shielding plate 7, so that the power transistor 4 can be driven in the same way as described above. Become.

In this case, since the battery 12 is used as a power source for light projection, the battery 12
In order to reduce the consumption of transistor 9,
is switched in synchronization with the primary short-circuit current of the ignition coil 1. That is, when a primary short-circuit current is not induced, the light projecting circuit using the battery 12 as a power source is off, and when a primary short-circuit current is induced, this light projecting circuit is turned on.

FIG. 4 shows an embodiment of a magnetic type light projecting circuit in place of the battery type light projecting circuit. This is the third
Transistor 9, resistor 11, battery 1 shown in the figure
The structure is such that 2 is removed. In addition, resistance 1
4 and various constants of the transistor 15 are appropriately selected. According to this, the driving of the control transistor 15 and the lighting of the light emitting element 16 are performed using the primary short circuit current as a power source, and the use of the transistor 9, resistor 11, and battery 12 can be omitted, simplifying the configuration and Cost reduction can be achieved.

As explained in detail above, according to the present invention,
The collector and emitter of a power transistor are connected to both ends of the primary winding of the ignition coil, respectively, and the base of this power transistor is connected to the midpoint between the resistor connected in series with both ends of the primary winding and the light receiving element. In the non-contact ignition circuit for an internal combustion engine, the light projecting means emits light to the light receiving element when the current flowing through the primary coil reaches a substantially peak value, and the light projecting means emits natural light and the natural light. This structure completely eliminates the instability of conventional ignition operation and the inability to ignite when natural light is used as a light projecting means. Effects such as being able to effectively suppress energy loss due to lighting of the light emitting element can be obtained.

[Brief explanation of the drawing]

Figure 1 is a non-contact ignition circuit diagram of a conventional internal combustion engine, which is the basis of this invention, Figure 2 a, b, c, and d are waveform diagrams of each part of the circuit, and Figures 3 and 4 are from the original. FIG. 2 is a non-contact ignition circuit diagram for an internal combustion engine showing an embodiment of the invention. DESCRIPTION OF SYMBOLS 1... Ignition coil, 4... Power transistor, 6, 13... Light receiving element, 7... Light shielding plate, 8... Light projecting means, 12... Battery, 16...
...Light emitting element.

Claims (1)

[Scope of utility model registration request] The collector and emitter of a power transistor are connected to both ends of the primary winding of the ignition coil, respectively, and the base of this power transistor is connected to the midpoint between the resistor connected in series to both ends of the primary winding and the light receiving element. In the non-contact ignition circuit for an internal combustion engine, the light emitting means emits a maximum level of light to the light receiving element when the primary short-circuit current flowing through the primary coil reaches a substantially peak value. A non-contact ignition circuit for an internal combustion engine comprising natural light and a light emitting element that lights up in synchronization with the primary short circuit current when the amount and brightness of the natural light decreases.