JPH04298680A - Ignition device for engine - Google Patents

Abstract

PURPOSE:To improve ignitability and combustibility of mixture gas and restrain to generate smoke fouling of an ignition plug by forming peaks of secondary voltage of an ignition coil at two positions. CONSTITUTION:In middle and low rotating speed territory of Ne<No, both a full transistor type igniter and a capacitor discharge type igniter(CDI) are simultaneously operated (S2, S10). Hereby, the secondary current of an ignition coil is instantaneously enlarged and also the large current value continues long, and hence smoke fouling of an ignition plug is restrained and ignitability and combustibility of mixture gas is improved. In this middle and low rotating speed territory, ignition timing is set on the retard side than the usual value in case of providing only one igniter, and also a fuel injection quantity is set less than the usual value (S5). In high rotating speed territory of Ne>=No, the CDI having quick build-up of secondary voltage only operated alone.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an ignition system for an engine, and more particularly to measures for improving the ignitability and combustibility of an air-fuel mixture.

0002

[Prior Art] Conventionally, as an ignition device for an engine,
For example, a transistor type ignition device is known as disclosed in Japanese Unexamined Patent Publication No. 1-142266. This method is a method in which a transistor is turned off at the ignition timing, the energization to the primary coil of the ignition coil is interrupted by this off operation, and a high voltage is generated in the secondary coil to ignite.

As another type of ignition device, there is a capacitor discharge type ignition device as disclosed in, for example, Japanese Unexamined Patent Publication No. 64-92577. This method charges a capacitor to a set voltage and discharges this charge to the primary coil of the ignition coil all at once at the ignition timing, thereby generating a high voltage in the secondary coil and igniting it.

0004

[Problems to be Solved by the Invention] However, although the transistor type ignition device can ensure relatively good combustion of the air-fuel mixture, the rise of the secondary voltage in the ignition coil is relatively slow, so the combustion temperature of the air-fuel mixture is low. The problem was that the spark plugs were smoldering and dirty. In addition, with the capacitor discharge type, the secondary voltage rises quickly, so it is possible to eliminate smoldering and contamination of the spark plug. There was a drawback that the value decreased.

The present invention has been made in view of the above-mentioned problems, and its object is to eliminate smoldering and fouling of the spark plug while ensuring good combustibility of the air-fuel mixture.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention includes a transistor type ignition device and a capacitor discharge type ignition device, both of which are operated simultaneously.

That is, as shown in FIG. 1, the specific solution of the invention according to claim 1 of the present application is to charge the capacitor C and transfer the charged electric charge to the primary coil of the ignition coil 3 at the ignition timing. A first ignition means 31 of a capacitor discharge type that discharges to ignite, and a transistor Tr is turned off at the ignition timing, and this off
The first ignition means 31 and the second ignition means 20 are configured to operate at the same time. .

Furthermore, as mentioned above, both ignition means 31,
When the ignition means 31 and 20 operate at the same time, in the invention according to claims 2 and 3, as shown in the same figure, each of the ignition means 31
, 20 operate independently, an ignition timing setting means 35 is provided to set the ignition timing to the retard side, and the fuel injection amount of the engine is set to a smaller amount. Furthermore, in the invention described in claims 4, 5, and 6, the timing for simultaneously operating both of the ignition means 31 and 20 is specified in an engine operating range where the engine speed is less than a set value, and In the region, either one of the ignition means 31 or 20 is operated independently, or in the region where both the ignition means 31 and 20 are operated simultaneously, the fuel injection amount of the engine is changed when the ignition means 31 and 20 are operated independently. The configuration is such that the amount is set to a relatively small amount.

[0009]

[Operation] With the above configuration, in the invention as claimed in claim 1,
At the ignition timing, in the ignition coil 3, a secondary voltage is initially generated based on the discharge of the capacitor C, and then a secondary voltage is generated based on the OFF operation of the transistor Tr. As a result, the secondary voltage that rises at the beginning of the ignition timing improves ignition performance, increases the combustion temperature of the air-fuel mixture, and eliminates smoldering and fouling of the spark plug. Further, even if the secondary voltage due to the discharge of the capacitor C decreases in a short time, the combustion of the air-fuel mixture is performed satisfactorily due to the secondary voltage based on the OFF operation of the transistor Tr. Moreover,
As mentioned above, since the secondary voltage peaks at two locations, the generation of these two secondary voltages together improves the ignitability and combustibility of the air-fuel mixture, and improves fuel efficiency. .

Furthermore, when both the transistor type and capacitor discharge type ignition means 31 and 20 are operated simultaneously,
As mentioned above, since the combustibility of the mixture is improved, even if the ignition timing is set to the retard side compared to when each ignition means 31 and 20 are operated individually, the combustibility of the mixture can be maintained well. The combustion temperature of the air reaches an appropriate value, the amount of NOx generated is reduced, and the emission performance is improved. In addition, when either one of the ignition means 31 and 20 fails, ignition is performed at the normal value ignition timing. Good combustibility of the air-fuel mixture is ensured even in the event of a failure. Furthermore, even if the fuel injection amount of the engine is set to a smaller amount than when each ignition means 31, 20 is operated independently, the fuel consumption is limited to a small amount while ensuring good combustibility of the air-fuel mixture. Fuel efficiency is further improved, and good combustibility of the air-fuel mixture is ensured even when either one of the ignition means 31, 20 fails.

In addition, simultaneous operation of both ignition means 31 and 20 is carried out only in the operating region where the engine speed is less than the set value, that is, in the region where the combustion of the air-fuel mixture tends to become unstable. While the combustibility of the air-fuel mixture is improved and good combustibility of the air-fuel mixture is ensured over the entire operating range, both ignition means 31 and 20 are activated simultaneously in the operating range where the engine speed is higher than the set value. The increase in load on the alternator due to alternator operation is suppressed, reducing the engine load.
Therefore, fuel efficiency will improve. Furthermore, if the capacitor discharge type ignition device 31 is used in the range of engine speeds above the set value, the ignition timing at high engine speeds can be accurately controlled because the secondary voltage rises quickly.

0012

[Effect of the invention] As explained above, claim 1 of the present application
According to the engine ignition system described, the transistor o
To eliminate smoldering contamination of a spark plug and to improve ignitability and combustibility of an air-fuel mixture by both the secondary voltage generated based on FF operation and the secondary voltage generated based on discharge of a capacitor. This makes it possible to improve fuel efficiency.

In particular, when a transistor type ignition system and a capacitor discharge type ignition system are operated simultaneously, good combustibility of the air-fuel mixture can be ensured by setting the ignition timing to the retard side compared to when the ignition system is operated independently. However, it is possible to suppress the generation of NOx and improve emission performance, and by setting the engine fuel injection amount to a small amount, it is possible to improve fuel efficiency while ensuring good combustibility of the air-fuel mixture. can.

Furthermore, if the simultaneous operation of both ignition devices is limited to the operating range where the engine speed is less than the set value, the load on the alternator and the engine load can be reduced in the high engine speed range above this operating range. In addition to further improving fuel efficiency, if the capacitor discharge type ignition device is operated independently in this high speed range, the ignition timing at high speeds can be improved due to the good secondary voltage rise characteristics. can be precisely controlled.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to FIG. 2 and the following drawings. FIG. 2 shows a schematic configuration diagram of an engine ignition system according to the present invention. In the figure, 1 is a spark plug, 2 is a distributor that distributes high voltage to the ignition plug 1, and 3 is an ignition coil, which has a first ignition coil 4 and a second ignition coil 5. Both ignition coils 4,
5 are connected in parallel.

Reference numeral 8 denotes a Hall type camshaft sensor, which is used to identify the first cylinder of the engine as shown in FIG. 3(a).
The signal SGC shown in FIG. 1 and the rotation speed signal SGT shown in FIG. 9 is an electromagnetic pickup type crankshaft sensor which outputs a rotational speed signal N shown in FIG. 3(c).

Further, reference numeral 11 is an engine control unit having a CPU therein, and receives three types of signals from both the sensors 8 and 9 mentioned above. The engine control unit 11
internally includes a waveform shaping circuit 12 that shapes the rotational speed signal N of the crankshaft sensor 9, and the rotational speed signal N shaped by the shaping circuit 12 and both signals SGC of the camshaft sensor 8.
, SGT, and a control circuit 13 for controlling the ignition timing and closing angle of the spark plug 1 and outputting an ignition timing signal IGT, and a backup circuit 14 in case of a failure. The engine control unit 11 has a function of controlling the amount and timing of fuel injection from the fuel injection valve 15 of the engine.

In addition, 17 is a full-transistor type igniter, which includes a power transistor Tr connected to the primary coil 4a of the first ignition coil 4 of the ignition coil 3, and a power transistor Tr connected to the primary coil 4a of the first ignition coil 4. The drive circuit 18 includes a drive circuit 18 that is turned on and off based on whether or not the ignition timing signal IGT from the control circuit 13 is received. Therefore, the ignition timing signal IGT is output from the control circuit 13 by the igniter 17 and the first ignition coil 4.
By turning off the power transistor Tr at the output ignition timing, the power supply to the primary coil 4a of the first ignition coil 4 is interrupted and the secondary coil 4 is turned off.
A second ignition means 20 is configured to ignite the spark plug 1 by generating a high voltage at the terminal b.

Note that in the igniter 17, 21
22 is a constant current circuit that is connected to the power transistor Tr and keeps the primary current value of the first ignition coil 4 constant; 22 is a lock prevention circuit that prevents lock failure when the power transistor Tr is on; 23 is a constant current circuit of the igniter 17; A failure detection circuit that detects a failure, the failure detection signal IGf2
is the backup circuit 1 of the engine control unit 11
4 is output.

Further, in FIG. 2, 28 is a capacitor discharge type igniter (hereinafter referred to as CDI),
The interior thereof includes a capacitor C connected to the primary coil 5a of the second ignition coil 5 of the ignition coil 3, a DC/DC converter 29 for charging the capacitor C, and a thyristor SCR. The capacitor C and the primary coil 5a of the second ignition coil 5 form a closed circuit. The thyristor SCR is controlled on and off by a trigger circuit 30, and the trigger circuit 30 operates based on the ignition timing signal IGT output from the control circuit 13.

Therefore, the capacitor C is charged in advance by the CDI 28 and the second ignition coil 5 using the DC/DC converter 29, and in this state, the thyristor SCR is activated at the ignition timing when the ignition timing signal IGT is output. By turning on the trigger circuit 30, the electric charge charged in the capacitor C is discharged to the primary coil 5a of the second ignition coil 5, and the secondary coil 5 is
A first ignition means 31 is configured to generate a high voltage at the terminal b and ignite the ignition plug 3.

As shown in FIG. 4, the operating characteristics of the full transistor type igniter 17 and the CDI 28 are such that the rise of the secondary voltage of the first ignition coil 4 is relatively slow in the former, and in the latter CDI 28. It has a characteristic of quick rise. As a result, as shown in Figure 5, the total secondary current obtained by combining the above two secondary voltages becomes a large current instantaneously, and has a characteristic that it maintains a relatively large current value even after a predetermined period of time has elapsed. .

Next, ignition timing control and fuel injection amount control by the engine control unit 11 will be explained based on the control flow shown in FIG.

After starting and reading the engine speed Ne and intake air amount Qa in step S1, step S1
In step S3, the engine speed Ne is compared with the set value No of the medium speed in step S3.
Control is performed thereafter, and in a high rotation region where Ne≧No, control is performed from step S19 onwards.

First, in the medium and low rotation range, step S
In step S3, it is determined whether or not the rotational speed signal SGT of the camshaft sensor 8 has been received, and only if it has been received, in step S4, the values of the failure flags F1 and F2 of each igniter 17 and 28 are determined, and F1=F2. If none of =0 indicates a failure, the ignition timing is read from the ignition timing map 1 stored in advance based on the engine speed and intake air amount in step S5. Here, the ignition timing map 1 is a full-transistor type (hereinafter abbreviated as full-transistor type) igniter 17 or a CD
A value retarded by a set value from the ignition timing when only I28 is used is stored. In addition, in step S5, the fuel injection amount is determined based on the fuel injection amount map in which the fuel injection amount is set to be smaller than the normal value in the case of the full-torque igniter 17 or the CDI 28 alone, and the injection amount is determined according to the engine speed and intake air amount at that time. is read, and the fuel injection valve 15 is controlled to achieve this injection amount.

On the other hand, when either F1=1 or F2=1 is a failure of the igniter, the ignition timing is read from a similar ignition timing map 2 in step S6. The ignition timing map 2 stores in advance normal ignition timing values when the full-travel igniter 17 or the CDI 28 is used alone.

Thereafter, in step S7, it is determined whether or not the read target ignition timing has been reached, and at this target ignition timing, steps S8 and S9 are carried out.
The failure flags F1 and F2 of igniter 17 or 28 respectively
When the value of F1=F2=0 is normal, the ignition timing signal IGT is output to both the full-travel igniter 17 and the CDI 28 in step S10, and both igniters 17 and 28 are operated simultaneously to ignite. have them do it.

[0028] Subsequently, step S11 and step S1
In step S13, it is determined whether or not the failure signal IGf1 is input from the CDI 28 or the failure signal IGf2 is input from the full-length igniter 17, and when the CDI 28 with IGf1=1 is in failure, the failure flag F1 is set to 1 in step S13, and In step S14, the fuel injection amount map is switched to a normal value map with a large injection amount. Similarly, when the full-throttle type igniter 17 with IGf2=1 fails, step S15
At the same time, the failure flag F2 is set to 1 in step S1.
At step 6, the fuel injection amount map is switched to a normal value map with a large injection amount, and the process returns.

[0029] Then, in step S8 above, C with F1=1
When the DI28 fails, the ignition timing signal IGT is output only to the full-throttle type igniter 17 in step S17, while when the full-type igniter 17 with F2=1 fails in step S9, the ignition timing signal IGT is outputted only to the full-throttle type igniter 17 in step S18
Outputting the ignition timing signal IGT only for 8,
Return.

Next, to explain the control in the high rotation speed region, in step S19, the rotation speed signal SG of the camshaft sensor 8 is
Only when T is received, the ignition timing is read from the ignition timing map 2 that stores the ignition timing of the normal value in step S20. Then, when the target ignition timing read above is reached in step S21, the value of the failure flag F1 is determined in step S22, and the CD with F1=0 is determined.
When the I28 is normal, the ignition timing signal IGT is output only to the CDI28 in step S23.
On the other hand, when the CDI 28 with F1=1 fails, the ignition timing signal IGT is output to the full-type igniter 17 instead in step S24, and the process returns.

Therefore, in step S5 of the control flow shown in FIG. 5, the engine speed is less than the set value (Ne<N
o) When both the full-throttle type igniter 17 and the CDI 28 operate simultaneously in the medium and low rotation speed range, the ignition timing is read from the ignition timing map 1, and the ignition timing is when the full-throttle type igniter 17 or the CDI 28 operates alone. The ignition timing setting means 35 is configured to set the ignition timing to a value that is retarded by a set value than the ignition timing setting means 35.
A fuel injection amount setting means 36 reads from a fuel injection amount map that is set to a smaller amount than the normal fuel injection amount when the I28 operates alone, and sets the fuel injection amount from the fuel injection valve 15 to a smaller amount. It consists of

Therefore, in the above embodiment, when the engine speed Ne is less than the set value No (Ne<No),
In the low rotation range, full tiger type igniter 17 and CDI2
8 operate simultaneously. By this, CDI2
With the rapid rise of the secondary voltage of the ignition coil 3 due to the ignition coil 8, the secondary current instantaneously becomes a large current as shown in FIG. Moreover, after that, the value of the secondary current continues to be relatively large due to the secondary voltage generated by the full-throttle igniter 17, so that good combustibility of the air-fuel mixture is ensured.

Furthermore, in the above-mentioned medium and low speed ranges, the ignition timing is read from the ignition timing map 1 and set to the retard side of the normal value, ensuring good combustibility of the air-fuel mixture. As the combustion temperature of the air-fuel mixture reaches the appropriate value, N
The amount of Ox generated is reduced, the emission performance is improved, and the amount of fuel injected from the fuel injection valve 15 is set to a smaller amount than the normal value, so fuel consumption is reduced while maintaining good combustibility of the air-fuel mixture. can be reduced and fuel efficiency can be improved. In addition, in this low rotation range, if either the full-torque igniter 17 or the CDI 28 is malfunctioning, both the ignition timing and the fuel injection amount are set to normal values, so it is possible to avoid the occurrence of the malfunction. Good combustibility of the air-fuel mixture can be ensured.

Furthermore, while the combustion of the air-fuel mixture tends to become unstable, both igniters 17 and 2 are
8 operates at the same time, the combustibility of the mixture is ensured well in this region, and the combustibility of the mixture is good in the entire operating range from low to high rotations, in addition to the high rotation range where the combustibility of the mixture is originally good. In addition to improving the combustibility of the air-fuel mixture, in the high rotation range where Ne≧No, only the CDI 28 operates independently and the full-throttle igniter 17 is stopped, so the load on the alternator is reduced and the engine The load is lighter and fuel efficiency is further improved.

Furthermore, in the high rotation range where Ne≧No, the CD
Since I28 operates independently, the secondary voltage at the ignition coil 3 rises quickly, and the ignition timing in this high rotation range can be controlled with high precision.

[Brief explanation of the drawing]

FIG. 1 is a complaint correspondence diagram.

FIG. 2 is an overall configuration diagram of the ignition device.

FIG. 3 is a diagram showing output signal waveforms of a camshaft sensor and a crank angle sensor.

FIG. 4 is a diagram showing a secondary voltage waveform of an ignition coil.

FIG. 5 is a diagram showing a secondary current waveform of an ignition coil.

FIG. 6 is a flowchart showing ignition timing control and fuel injection amount control.

[Explanation of symbols]

Claims (6)

[Claims] 1. A first ignition means for charging a capacitor and discharging the charged charge to a primary coil of an ignition coil to ignite the ignition coil at the ignition timing; and a transistor for turning off the ignition coil at the ignition timing; and a second ignition means for igniting the primary coil by cutting off current to the primary coil, the first ignition means and the second ignition means operating simultaneously. 2. When the first ignition means and the second ignition means operate simultaneously, the ignition timing is retarded compared to the ignition timing when the first ignition means or the second ignition means operate independently. 2. The engine ignition system according to claim 1, further comprising ignition timing setting means set on the side. 3. When the first ignition means and the second ignition means operate simultaneously, the fuel injection amount of the engine is compared to the fuel injection amount when the first ignition means or the second ignition means operate alone. 2. The engine ignition system according to claim 1, further comprising fuel injection amount setting means for setting the fuel injection amount to a small amount. 4. The region where the first ignition means and the second ignition means operate simultaneously is the region where the engine speed is less than a set value, and in the region where the engine speed is higher than the set value, the first ignition means or the second ignition means operate simultaneously. The engine ignition system according to claim 1, wherein the two ignition means operate independently. [Claim 5] In a region where the engine speed is higher than a set value,
5. The engine ignition system according to claim 4, wherein the first ignition means operates independently. 6. A region where the first ignition means and the second ignition means operate simultaneously is a region where the engine speed is less than a set value, and in a region where the engine speed is higher than the set value, the first ignition means or the second ignition means operate simultaneously. The two ignition means operate independently, and in a region where the engine speed is less than the set value, the fuel injection amount becomes smaller than the fuel injection amount when the first ignition means or the second ignition means operate independently. 2. The engine ignition system according to claim 1, further comprising fuel injection amount setting means for setting the fuel injection amount.