JPH0217710B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an ignition system for an internal combustion engine, and more particularly to an improvement technique for a so-called distributorless ignition system of the Harteitz type. Details of conventional ignition devices of this type are, for example,
This is described in SAE-780327 (paper number of the American Society of Automotive Engineers), etc., but to briefly explain it with reference to FIG. 1, the two high voltage output terminals 1a on the secondary side of the ignition coil 1, Each of 1b is connected to 1 with different poles connected to each other.
A set of high voltage diodes D ₁ , D ₃ and D ₂ , D ₄ are connected respectively. And these two sets of high voltage diodes D ₁ ~
Spark plugs 2a to 2d are connected between the other pole of _D4 and the ground, respectively. In addition, in a 4-cylinder internal combustion engine, the spark plug 2b
is for the first cylinder (#1), spark plug 2c is for the second cylinder (#2), spark plug 2a is for the third cylinder (#3), and spark plug 2d is for the fourth cylinder (#4).
It is for use. Terminals 1c, 1 at the winding end on the primary side of the ignition coil 1
d is provided with two systems of ignition circuits 3, and the primary current supplied from the battery 4 via the ignition switch 5 and center tap 1e is alternately turned on and off. The direction is alternately switched between the direction indicated by the solid line arrow and the direction indicated by the dashed line arrow. The ignition circuit 3 is connected to the rotor (in the case of a 4-cylinder engine, 1/2 of the engine rotation speed) in the ignition signal generator 6.
protrusions 7a, 7 with a 180° phase shift of 7)
By moving a relatively close to the pick-up coils 8 and 9, which are 90 degrees out of phase with each other, the period in terms of the crank angle output from the pick-up coils 8 and 9 is 360 degrees CA and 180 degrees A to each other. Ignition signals S _F1 and S _F2 having a phase difference of are input. Comparator 1 for determining the conduction angle in the ignition circuit 3
0 and 11 are the ignition signals S _F1 and S _F2 output from the pickup coils 8 and 9, respectively, and predetermined reference values.
Comparing S _r1 and S _r2 (S _r1 = S _r2 ), S _F1 ≧ S _r1 ,
Conduction angle signals S ₁ and S ₂ that become high level “H” are output only when S _F2 ≧S _r1 . The switching circuit 12 is turned on only while the conduction angle signal S ₁ from the comparator 10 is at a high level "H" to flow the primary current in the direction indicated by the solid line arrow to the primary side of the ignition coil 1, and when it is turned off, the ignition is started. On the secondary side of coil 1,
High voltage output terminal 1a is positive, high voltage output terminal 1b
Generates a high voltage (15~25KV) V _P1 that is negative. On the other hand, the switching circuit 13 is turned on only while the conduction angle signal S ₂ from the comparator 11 is at a high level "H", flows the primary current to the primary side of the ignition coil 1 in the direction indicated by the broken line arrow, and is turned off. At times, a high voltage (15 to 25 KV) V _P1 is applied to the secondary side of the ignition coil 1, with the high voltage output terminal 1a being negative and the high voltage output terminal 1b being positive.
to occur. Therefore, when the switching circuit 12 is turned off and a high voltage V _P1 is generated on the secondary side of the ignition coil ₁ , the _first Since the electrodes of the ignition coils 2b and 2d for the fourth cylinder simultaneously break down, discharge current due to capacitive discharge and subsequent inductive discharge flows in the direction indicated by the solid line arrow. Furthermore, when the switching circuit 13 is turned off and a high voltage V _P2 is generated on the secondary side of the ignition coil 1, the high voltage diode becomes forward biased.
Due to the action of D ₂ and D ₃ , the electrodes of the ignition coils 2c and 2a for the second and third cylinders break down at the same time, so the discharge current due to capacitive discharge and subsequent inductive discharge is shown by the broken line arrow. flow in the direction. In the case of a 4-cylinder engine, intake every 180°CA,
Compression, expansion, and exhaust strokes are 180℃ for each cylinder.
Since the spark plugs 2b and 2d for the first and fourth cylinders break down at the same time, if the first cylinder is in the compression stroke and the fourth cylinder is in the exhaust stroke, then the first cylinder will be in its spark plug 2b. The discharge spark from the ignition plug 2d of the fourth cylinder becomes wasted fire. Similarly, spark plugs 2c, 2 for the second and third cylinders
When cylinders a break down at the same time, if the third cylinder is in the compression stroke and the second cylinder is in the exhaust stroke, the third cylinder will be ignited by its spark plug 2a, and the discharge spark of the second cylinder's spark plug 2c will be discarded. (wasted fire)
becomes. The following table summarizes the ignition behavior of the Harteitsug type ignition system as described above.

[Table] By the way, in the case of the above-mentioned Harteitsug type ignition system, in addition to the effect of eliminating the distributor, it is also effective in reducing the pressure increase at the time of ignition due to the high compression ratio of the engine and the use of a turbo engine. However, like other ignition devices equipped with a distributor such as the Kettering method, the ignition energy during inductive discharge is low at less than 30 mJ, and the discharge period is about 1 to 1.5 msec. Due to its short length, the following problems arose: In other words, when igniting under the conditions described above,
When the engine is under low load, it may not be possible to reliably ignite a lean mixture during idling, so in order to reduce the misfire rate, the ignition timing during idling must be delayed. If this is done, fuel consumption will increase. In addition, misfires sometimes occurred when a lean mixture was generated due to a sudden change in the mixture during transient operation, or during exhaust gas recirculation, causing a surge. This invention was made in view of the above-mentioned background, and it is equipped with a DC-DC converter for reinforcing ignition energy in the Harteitsug type ignition system, thereby improving engine performance, especially fuel efficiency during idling. The aim is to improve combustion efficiency and stabilize combustion during lean mixture operation and exhaust gas recirculation (EGR) operation. Therefore, in the ignition system for an internal combustion engine according to the present invention, in the Harteitzch type ignition system as described above, the capacitor that charges the high voltage output in the DC-DC converter is simultaneously discharged.
Connect each of the terminals on the high-voltage diode connection side of the four spark plugs, and connect a diode between each of these connection points and both ends of the capacitor to the pole on the spark plug side of each of the four high-voltage diodes. They are connected so that the same poles are facing. Embodiments of the present invention will be described below with reference to FIG. 2 and subsequent drawings. FIG. 2 is a circuit configuration diagram showing an embodiment of the present invention. In this figure, parts and signal names corresponding to those in FIG. 1 are given the same reference numerals, and their explanations will be omitted. First, the converter control circuit 14 and the DC-DC converter 15 will be explained. Comparator 16 in converter control circuit 14
is the reference value S _r3 (S _r3 > S _r1 , S _r2 : S _r1 , S _r2 is the third
ignition signals output from the resistors R ₁ and R ₂ (see Figures A and B) and the pickup coils 8 and 9.
The ignition signal _{S F3 (} see _{Fig . 3} It consists of an operational amplifier OP that compares the signal S _F3 (see _{Figure 3)} and outputs a reference signal S ₃ (see Figure 3 H) for determining when to start converter oscillation, which becomes a high level "H" only when S F3 ≧ S r3. Note that the reference signal output from this comparator 16
At each falling point of S ₃ , the switching circuits 12 and 13 operated by the conduction angle signals S ₁ and S ₂ shown in FIG.
A time τ ₁ (for example, 0.5 μsec to 1 msec) has passed since the time when _the next currents I 1 and I ₂ (see E and F in FIG. 3) are cut off. The reason for doing this is that the oscillation rise delay time of the DC-DC converter 15 (for example, 150
DC-DC converter 15
This is to ensure that the primary currents I ₁ and I ₂ are cut off without delay. A monostable multivibrator (M/M) 18 for determining the oscillation period of the DC-DC converter 15 is a resistor.
_R3 , an M/M dedicated IC called "HD74121" made by Hitachi, which consists of an inverter _G1 , an AND gate _G2 , and a flip-flop circuit FF, and a resistor R for setting a time constant to determine the pulse width. ₄ and a capacitor _C1 , and is triggered at each falling edge of the reference signal _S3 from the comparator ₁₆ , and maintains a high level "H" for a time τ ₂ from each falling point. (See Figure 3). As for the value of time τ ₂ , the effect of injecting ignition energy by the DC-DC converter 15 is most noticeable when the engine is idling (500 to 800 rpm), and the injection time at that time is 3 to 6 msec. Since it is effective, a value in the range of 3 to 6 msec is chosen. The switching transistor 19 is an M/M18
The coil CL and _the capacitor C _{2 are turned on and off each time the control signal S 4 rises} from "L" to "H" as shown in FIG. , _C3 , the voltage of the battery 4 applied to the collector is supplied to the DC-DC converter ₁₅ for a time τ2. The DC-DC converter 15 is constituted by a self-oscillating converter that combines a Royer circuit with a bridge rectifier circuit, and operates as follows. In other words, a resistor is connected to the center tap of the primary winding _L1 of the step-up transformer T and the center tap of the feedback winding _Lf .
When voltage is applied through R ₅ , R ₆ and capacitor C ₄ , transistors T _r1 and T _r2 inserted between both ends of the primary winding L ₁ and ground, respectively, are activated by the action of the feedback winding L _f . It alternately turns on and off to alternately reverse the direction of the excitation current of the step-up transformer T, thereby generating a high-voltage alternating signal across the secondary winding _L2 , which is then passed to the bridge rectifier REC. After converting to direct current, the capacitor _C5 is charged to output a high direct current voltage _V0 (1 to 4 KV). Next, the connection of the capacitor _C5 in the DC-DC converter 15 to the spark plugs 2a to 2d will be explained. In other words, two spark plugs 2 that discharge simultaneously
b, 2d and 2c, 2a high voltage diode D ₁ ,
A capacitor _C5 is connected between the terminals P1- _P4 and _P2 -P3 on the connection side of _{D4 , D2} , and _{D3, respectively} . However, in order to prevent the charging voltage V ₀ of the capacitor C ₅ from being consumed on the secondary side of the ignition coil 1, the positive terminal of the capacitor C ₅ is connected to the terminals P ₁ and P to which the cathodes of the high voltage diodes D ₁ and D ₂ are connected. The negative terminal _{of 2} is connected to terminals P ₃ and P ₄ to which the anodes of high voltage diodes D ₃ and D ₄ are connected, respectively. Then, high-voltage steering diodes _D7 to D10 are connected between each connection point of this capacitor _C5 and both ends of the capacitor _C5 , respectively, and high-voltage diodes _D1 to _D10 are connected to each other.
Connect _D4 so that the same pole faces the poles of spark plugs 2a to 2d to specify the direction of the discharge current of capacitor _C5 , and connect the spark plugs 2a to 2d of ignition coil 1
The high voltages V _P1 and V _P2 that are generated alternately on the next side are prevented from being applied to the capacitor _C5 . In this way, at the timing of cutting off the primary side of the ignition coil 1 shown in FIG.
An induced high voltage V _P1 is generated on the next side, and due to the action of the high voltage diodes D ₁ and D ₄ , the electrodes of the spark plugs 2b and 2d of the first and fourth cylinders break down and an induced discharge is started. and DC-DC converter 1
The discharge current due to the high voltage V ₀ that is being charged without delay to the capacitor C ₅ of No. 5 is applied to the steering diode D ₈ , terminal P ₁ , spark plug 2b for the first cylinder,
It flows through the loop of the spark plug 2d for the fourth cylinder, the terminal P ₄ , and the steering diode D ₉ . As a result, the discharge current i _s flowing through the spark plugs 2b and 2d becomes as shown in _FIG .
sec), and the discharge energy also increases by the amount shown by hatching. In addition, an induced high voltage V _P2 is applied to the secondary side of the ignition coil 1.
occurs, and the electrodes of the spark plugs 2c and 2a for the second and third cylinders break down due to the action _of the high-voltage diodes D ₂ and D ₃ and inductive discharge starts. A discharge current due to the high voltage V ₀ that is not being charged flows through the steering diode D ₇ , the terminal P ₂ , the spark plug 2c for the second cylinder,
It flows through a loop of the spark plug 2a for the third cylinder, the terminal P ₃ , and the steering diode D ₁₀ . As a result, the discharge current i _s flowing through the spark plugs 2c and 2a _becomes as shown in FIG. It increases by the amount shown. Due to this kind of discharge, the advantages of the Harteitsug type ignition system include, for example, low noise, as well as the ability to reliably ignite a lean air-fuel mixture during idling without delaying the ignition timing. This not only improves fuel efficiency, but also stabilizes combustion by preventing misfires during transient operation or exhaust gas recirculation operation. In addition, the DC− shown in Figure 3
In the waveform of the output high voltage V ₀ of the DC converter 15, the voltage level of the shaded portion is the load oscillation voltage, and the other voltage levels are the no-load oscillation voltage. Moreover, the waveforms shown in FIG. 3 are the discharge voltage _vs at each of the spark plugs 2a to 2d. Furthermore, the diode _D11 connected between the negative terminal of the capacitor _C5 and the ground in the DC-DC converter 15 in FIG.
This is to prevent current from flowing around from the ground side terminals a to 2d. Furthermore, although the above embodiment has been described for a four-cylinder engine, it can be similarly applied to a six-cylinder engine or an eight-cylinder engine. In addition, in the case of an 8-cylinder engine, prepare 2 sets of the Harteitsug type ignition system (excluding the DC-DC converter 15 and converter control circuit 14) shown in Figure 2, and in the case of a 6-cylinder engine, prepare 1 1/2 sets. do. In the above embodiment, each component except the battery 4, ignition switch 5, ignition signal generator 6, and spark plugs 2a to 2d may be integrally molded. As explained above, in the ignition system for an internal combustion engine according to the present invention, since the DC-DC converter for reinforcing and injecting ignition energy into the Halteitsug type ignition device is provided, the unique effects of the Halteitsug type ignition device, namely, In addition to the effect of reducing noise by not using a distributor, the ignition timing can be optimized over the entire operating range, thereby improving fuel efficiency and driving performance. Therefore, by using this ignition device, it is possible to improve the marketability of a wide range of vehicle types, from popular cars to luxury cars and sports-type cars.

[Brief explanation of drawings]

FIG. 1 is a circuit configuration diagram showing an example of a Harteitsch type ignition device, FIG. 2 is a circuit configuration diagram showing an embodiment of the present invention, and FIG.
FIG. 4 is a signal waveform diagram of each part for explaining the operation of the figure. 1... Ignition coil, 2a to 2d... Spark plug, 3... Ignition circuit, 4... Battery, 6... Ignition signal generator, 14... Converter control circuit,
15...DC-DC converter, _D1 to _D4 ...High voltage diode, _D5 , _D6 ...Diode for rectification,
_D7 to _D10 ... Steering diode.

Claims (1)

[Claims] 1. A pair of high voltage diodes each having one different pole connected to each of the two high voltage output terminals on the secondary side of the ignition coil, and
A spark plug is connected between the other pole of each of these two sets of high-voltage diodes and the ground, and the direction of the primary current of the ignition coil is alternately switched. In an ignition system for an internal combustion engine of the Harteitsug type, which discharges the spark plugs at the same time, a capacitor for charging the high-voltage output of the DC-DC converter is connected between the high-voltage diode connection side terminals of the two spark plugs that are discharged at the same time. and a diode is connected between each of these connection points and both ends of the capacitor so that the same pole faces the spark plug side pole of each of the high voltage diodes. igniter.