JPS62165574A - Ignition device for internal combustion engine - Google Patents

Abstract

PURPOSE:To restrain carbon from being built up on a spark plug, by providing a capacitive discharge type first igniter and a voltage transformation type second igniter so that capacitive electric discharge in a short time is used as electric discharge for ignition at the termination of a compression stroke during cold engine operation. CONSTITUTION:An igniter 21 for a discharge type first ignition device and an igniter 22 for a voltage transformation type second ignition device are pro vided in a stage after an ECU 1 which receives detection signals from a rotation al angle sensor 8, a water temperature sensor 9 and an intake-air pressure sensor 11 and calculates an ignition timing and a clean electric discharge timing which satisfy operating conditions. Ignition coils 31, 33; 32, 34 in the first and second ignition devices are set in pairs, and the high voltage side of the ignition coils 31 and 32 or 33 and 34 is connected to a high voltage cord which is con nected in a wired OR pattern. Further, during, for example, cold engine opera tion the second coils 32, 34 effect a long time electric discharge in a suction stroke, and the first coils 31, 32 effect a short time electric discharge at the ignition timing.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ignition system for an internal combustion engine, and in particular, to an ignition system for an internal combustion engine that ensures ignitability of the ignition system in a partial load region (lean region), while at the time of cold operation, during startup, The present invention relates to an ignition device for an internal combustion engine that is capable of preventing a spark plug from smoldering under high load conditions (rich region) and reducing discharge energy.

[Prior Art and Problems to be Solved by the Invention] Ignition devices for internal combustion engines that take measures to prevent spark plugs from collapsing are already known. - For example, a transformer-type ignition device is used to lengthen the spark connection time, and while ensuring the discharge for ignition at the end of the compression process, the spark plug is cleaned by the discharge at the end of the suction process. In this case, the discharge energy for cleaning is set larger than the discharge energy for ignition.

However, such large discharge energy deteriorates the energy efficiency of the entire ignition system, resulting in an increase in the power generation time of the alternator and a deterioration in fuel efficiency. That is, as the spark connection time of the ignition device is lengthened when the engine is cold, the insulation resistance of the spark plug decreases. This phenomenon can be explained as follows. If there is turbulence in the combustion chamber, the burned gas that ignited at the beginning of the spark discharge will ride the turbulence of the air-fuel mixture and move away from the spark plug, causing flame propagation to proceed.

On the other hand, unburnt air-fuel mixture is flowing near the spark plug, but as the spark continues, the ignition process continues, and some of the air-fuel mixture in the middle of combustion is caused by the rise of the piston and the narrow space in the combustion chamber. The spark is forced into the nozzle, extinguishes the flame, turns into carbon, and accumulates around the insulator, resulting in spark discharge that promotes smoldering of the spark plug.

This causes the problem of worsening fuel efficiency as described above.

Means and operation for solving the problem c] The present invention is an ignition device for an internal combustion engine that solves the above problems, and includes a rotation angle sensor, an intake pressure sensor, a water temperature sensor, and a rotation angle sensor for detecting each operating condition. An electronic control circuit (ECU) that has a starter and outputs a control signal to each actuator according to each operating condition according to a signal from the starter;
A first ignition device that discharges a spark connection time of 1500 μsec or more and a spark energy of 30 mJ or more;
Equipped with a high-pressure cord with a wired OR connection between the ignition device and the second ignition device, and a spark plug installed in each cylinder, it is suitable for various operating conditions such as cold, warm, light load, and high load. Accordingly, the first ignition device and the second ignition device are variously selected and discharged at the end of the intake stroke and the end of the compression stroke.

〔Example〕

FIG. 1 is a block diagram of an embodiment of an ignition device for an internal combustion engine according to the present invention. In Figure 1, 1 is an electronic control circuit (
ECU), which is mainly composed of a computer, receives the engine rotation angle from the rotation angle sensor 8, the intake pipe pressure from the intake pressure sensor, the cooling water temperature from the water temperature sensor 9, and the signal from the starter 10 when starting the engine. manually,
Then, the ignition timing and clean discharge timing suitable for each operating condition are calculated. The rear stage is provided with a first ignition device consisting of a DC-DC converter 23 for boosting the DC voltage, an igniter 21, and ignition coils 31 and 33, and a second ignition device consisting of an igniter 22 and ignition coils 32 and 34. 1st
The ignition device is a capacitive discharge type ignition device, and the ignition coil 31.
33 is passed as the primary current, and then the voltage is boosted 100 times on the secondary side.
. . , a high voltage with a short discharge time (30 μsec) is generated, and this is applied to each spark plug 4 to cause discharge.

The second ignition device is a commonly used transformer type ignition device, and the primary current of 12V is applied to the ignition coil 32.34.
The magnetic energy is stored in the iron core of the spark plug 4, and the high voltage (approximately 40 KV) generated by the back electromotive force when the secondary current is turned off causes a voltage drop in the spark plug 4, and then the magnetic energy stored in the iron core is released. As a result, the discharge time is as long as 2m5ec. Ignition coil 31.33 of the first ignition device and ignition coil 3 of the second ignition device
2.34 consists of a pair, ignition coil 31 and 32.3
The high voltage sides of 3 and 34 are high voltage diodes 313 to 3, respectively.
4a are built in, and are connected by high voltage cords 71 and 72 connected with wired OR, and the other end is connected to each spark plug 4.

FIG. 2 is a signal timing chart of the device shown in FIG.

In FIG. 2, (A) is a cold state, (B) is a warm state under a light load, and (C) is a warm state under a high load and at startup.

First, in (A), the cooling water 40 is measured by the water temperature sensor 9.
In cold conditions below ℃, first, at the end of the intake stroke, the ECU outputs 1Gt2 shown in 6 to the igniter 22, which is the second ignition device, and the ignition coil 32 or 34 discharges the spark plug 4 as shown by I in C. A long discharge is performed to burn off the carbon adhering to the insulator of the spark plug 4. Thereafter, at the end of the compression stroke, the first ignition device is activated by iGt shown in a, and the ignition coil 31 or 32
The high voltage generated at is applied to the ignition plug 4, and a discharge is performed with a high secondary current value and a short discharge time, as shown by ■ in C. At this time, the mixture is rich (air-fuel ratio 9-10
Since the secondary current value is high, the mixture can be reliably ignited even if the discharge time is short, and since the discharge is not performed more than necessary, carbon buildup due to discharge around the spark plug is prevented. There is no carbon formation, and the accumulation of carbon on the insulator of the spark plug can be suppressed. As a result, less energy is needed for the discharge to clean the carbon at the end of the suction process of the next cycle, making it possible to downsize the second ignition device.

Next, in (B), the cooling water temperature is 4 from the water temperature sensor 9.
0°C or higher, the intake pipe negative pressure is 1100 from the intake pressure sensor 11.
During a warm light load of less than 11 g, the first ignition device, the DC-DC converter 23, igniter 21, and ignition coil 31.33, do not operate at all, and the second ignition device, the igniter 22, does not operate as shown in d. and ignition coil 32.3
4, a 1Gtz signal not shown in C from the ECU causes a discharge as shown in I of f, which has a long discharge time, at the ignition timing at the end of the compression process. This is because the air-fuel ratio is 14.5 to 18 at this time, and the fuel is in a lean state, so the discharge is carried out for a long time to prevent blowout.

Further, in (C), the water temperature sensor 9 and the intake pressure sensor 11 indicate that the cooling water temperature is 40°C or higher and the intake pipe negative pressure is -110°C.
During warm high loads of 0 mmHg or more and when starting from the starter 10, the igniter 2, which is the second ignition device, is activated.
2. The ignition coils 32 and 34 do not operate at all as shown in h, and only the first ignition device, the DC-DC converter 23, the igniter 21, and the ignition coils 31 and 33 are in EC mode.
A short capacitive discharge with a high secondary current value and a short discharge time is performed at the ignition timing at the end of the compression stroke by the iGt signal shown at g from U. Especially during warm high load conditions, the air-fuel ratio of the air-fuel mixture is around 12.5, and the air-fuel mixture is in good condition for ignition, so ignition can be ensured.Moreover, as shown in ■■ in i, the discharge time is short and the current value is large. The timing at which the air-fuel mixture starts to burn is very stable, the generated torque is generally high at high loads, and the timing at which the mixture starts to burn is very stable and torque fluctuations are noticeable.
However, in the present invention, this problem is improved, and furthermore, since the discharge is short under conditions of high heat load, it is possible to suppress electrode wear of the spark plug.

〔Effect of the invention〕

According to the ignition device for an internal combustion engine according to the present invention, the discharge for igniting at the end of the compression stroke when cold is made into a capacitive discharge with a short discharge time, thereby suppressing carbon accumulation on the spark plug and reducing the intake stroke. It is easy to clean the spark plug by clean discharge at 3 liters, and the ignition device for clean discharge can be made smaller and lighter, reducing costs.
This reduces the electrical load used by the ignition system, which reduces the power generation time of the alternator and improves the fuel ratio. In addition, by shortening the discharge time under conditions of high thermal load where the electrodes of the spark plug tend to wear out during warm high loads, electrode wear can be suppressed, greatly extending the life of the spark plug. At the same time, combustion fluctuations at high torque can be reduced, and stable drivability can be obtained. Furthermore, by using a capacitive discharge type ignition device for one of the ignition devices, the ignition coil can be made smaller, which also has the effect of improving mountability on the engine.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of an ignition system for an internal combustion engine according to the present invention, and FIG. 2 is a signal timing chart of the system shown in FIG. (Explanation of symbols) 1...Electronic control circuit, 2.21.22...Igniter, 3.31-34...Ignition coil, 4...Spark plug, 7...High voltage cord, 8. ...Rotation angle sensor, 9...Water temperature sensor, 10...Starter, 11...Intake pressure sensor.

Claims (1)

[Claims] 1. An ignition system for an internal combustion engine, which includes a capacitive discharge type first igniter, a transformer type second igniter, and first and second ignition coils connected to these in a wired OR, and when the engine is cold. During the intake process, the second coil performs a long-time discharge, the first coil performs a short-time discharge at the ignition timing, and during warm light load, the second coil performs a long-time discharge at the ignition timing, 1. An ignition device for an internal combustion engine, characterized in that the first coil performs a short discharge at the ignition timing during warm high load and startup.