JPH0533748A - Ignition timing control device for engine - Google Patents

Abstract

PURPOSE:To improve output and fuel consumption without causing knocking, in an engine using fuel containing alcohol. CONSTITUTION:At a high load, an ignition timing correcting quantity (TH) is respectively set, to plus side (spark advance) in low engine speed range, and to minus side (spark retard) in high engine speed range, the higher alcohol concentration is. Meanwhile, at a low load, a certain correcting quantity is set on the spark advance side regardless of engine speed N.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition timing control system for an engine using alcohol-containing fuel.

[0002]

2. Description of the Related Art Generally, in an engine that uses gasoline, the ignition timing is set to an advanced side as the engine speed increases, and is set to a constant advanced angle at a predetermined speed or higher. On the other hand, in an engine using alcohol-containing fuel, alcohol has a higher octane number than gasoline, so that a compression ratio is set higher than that of an engine using gasoline. Therefore, in the case of an engine with such a high compression ratio,
If the ignition timing is set to be the same as that of an engine using gasoline, preignition, knocking, etc. will occur especially in a high rotation range. Therefore, conventionally, in an engine using alcohol, it is known that the ignition timing is retarded on the high rotation side as compared with an engine using gasoline to prevent the occurrence of pre-ignition and the like. There is. For example, actual development Sho 63-193
The ignition timing control device for an internal combustion engine disclosed in Japanese Patent No. 777 is an example thereof, and in the one described in the publication, the advance characteristic when alcohol is used is equivalent to that for gasoline at low rotation speed. , The higher the rotation, the larger the retard amount compared to gasoline.

[0003]

By the way, when alcohol is used, the required ignition timing is shifted to the advance side compared to gasoline due to the high knock resistance of alcohol in the low rotation range. . However, the conventional ones, including those described in the above publications, are particularly set because the ignition timing correction amount when alcohol is used is set to be equivalent to that of gasoline in the low rotation range. There has been a problem that the output and the fuel consumption are reduced in the low rotation range.

The present invention has been made in view of the above problems, and it is an object of the present invention to provide an ignition timing control device for an engine which can improve output and fuel efficiency without causing knocking.

[0005]

According to the present invention, as shown in FIG. 2, the required ignition timing when an alcohol-containing fuel (M85) is used is lower than that when gasoline (G100) is used. Focusing on the fact that it has a characteristic that it is on the advance side from the high knock resistance of alcohol in the range, on the other hand, it is on the retard side from the speed of the combustion speed in the high rotation range, especially in the low rotation range. When the alcohol concentration is high, the ignition timing is advanced with respect to when it is low, and its configuration is as shown in FIG. That is, an engine ignition timing control device according to the present invention is an engine ignition timing control device that uses an alcohol-containing fuel, and includes an engine speed detecting means for detecting an engine speed and an engine speed detecting means. Based on the outputs of the ignition timing control means for controlling the ignition timing of the engine based on the output, the alcohol concentration detecting means for detecting the alcohol concentration in the used fuel, the engine speed detecting means and the alcohol concentration detecting means, When the alcohol concentration is high at low rotation speed, the ignition timing correction means for correcting the ignition timing setting by the ignition timing control means to the advance side is provided.

It is preferable that the ignition timing correction means further corrects the ignition timing setting by the ignition timing control means to the retard side when the alcohol concentration is high at high engine speed.

In addition to the above construction, load detecting means for detecting the engine load is provided, and based on the outputs of the engine speed detecting means, the load detecting means and the alcohol concentration detecting means, at the time of high load, at the time of low engine rotation. When the alcohol concentration is high, the ignition timing control means corrects the ignition timing setting to the advance side, and when the engine concentration is high and the alcohol concentration is high at high engine speed, the ignition timing setting is corrected to the retard side. It is also possible to employ a configuration including an ignition timing correction unit that corrects the ignition timing setting to the advance side when the alcohol concentration is high under load regardless of the engine speed.

[0008]

When the alcohol concentration in the fuel used is high, the ignition timing is corrected to the advance side when the engine is running at a low speed compared to when the alcohol concentration is low, so that the ignition timing is properly controlled in the low speed range, leading to knocking. Output and fuel efficiency are improved.

Further, if the ignition timing is corrected to the retard side when the alcohol concentration is high and the alcohol concentration is low at the time of high engine rotation, the optimum ignition timing is set regardless of the engine rotation, and knocking occurs. Output and fuel efficiency are improved.

Further, at high load, the ignition timing is corrected to the advance side at low engine speed and retarded at high engine speed, and at low load, the ignition timing is corrected regardless of the engine speed. Is adjusted to the advance side, the optimum ignition timing according to the engine rotation is set at high load, while the ignition timing of a predetermined advance amount is set at low load, knocking regardless of engine load. Is prevented and output and fuel efficiency are improved.

[0011]

Embodiments Embodiments will be described below with reference to the drawings.

FIG. 3 is an overall system diagram of an embodiment of the present invention.

In this embodiment, as shown in FIG.
A spark plug 3 is provided in the combustion chamber 2 of the engine 1, and the spark plug 3 is connected to an igniter 4 via a distributor. An intake passage 5 and an exhaust passage 6 communicate with the combustion chamber 2. An injector 7 for injecting fuel is provided in the intake passage 5. Further, the exhaust passage 6 is provided with two catalytic converters 8a, 8b for purifying the exhaust gas, and an O ₂ sensor for detecting the oxygen concentration in the exhaust gas is provided further upstream of the catalytic converter 8a on the upstream side. 9 is provided.

A fuel passage 11 for guiding fuel from a fuel tank 10 is connected to the injector 7. Fuel tank 1
A fuel pump 12 is disposed in the fuel cell 0, and the fuel passage 11 is connected to the discharge side of the fuel pump 12. Further, a fuel filter 13 is provided in the middle of the fuel passage 11, and an optical fuel sensor 14 is provided downstream of the fuel filter 13. The fuel sensor 14 detects the alcohol concentration in the fuel based on the refractive index of the light projected on the fuel. In addition, the fuel passage 11
A return passage 15 is connected to the fuel tank 10 and a pressure regulator 16 for adjusting the fuel pressure is provided at the connection portion.

The igniter 4 and the injector 7 are operated by a control signal from a control unit 17 composed of a microcomputer. The control unit 17 uses the output signal of the O ₂ sensor 9 and the output signal of the fuel sensor 14 as well as the engine rotation signal from the engine rotation sensor as the information for calculating the control signal.
A throttle opening signal is input from the throttle sensor and an engine water temperature signal is input from the water temperature sensor.

In this embodiment, as described above with reference to FIG. 2, the fuel containing 85% alcohol (M85).
In view of the characteristic that the required ignition timing (Ig.T) of (1) is advanced in the low speed range and is retarded in the high speed range with respect to that of 100% gasoline fuel (G100), Ignition timing correction amount ( _TH ) at high load
As shown in Fig. 4, in the low speed range, the plus (advance) side is
In the high rpm range, set each to the minus (retard) side.
Further, the ignition timing correction amount ( _TL ) at the time of low load is set to a constant correction amount on the advance side regardless of the engine speed (N). Here, in the case of the present embodiment, FIG.
As shown in, the value of T _H in the high rotation range, that is, the retardation amount is set to be a substantially constant value even when the rotation speed increases.

The ignition timing is basically calculated from the engine speed and the load, and the correction based on the alcohol concentration as described above is added to it, and other corrections such as water temperature correction are added to the final ignition timing. The ignition timing is set.

Next, the above control of this embodiment will be described with reference to the flow chart of FIG. Note that S101 to S10
Reference numeral 8 indicates each step.

In this flow, when starting, engine speed (N), load (T
_PK ), water temperature ( _THW ) and alcohol concentration (C) are read (S101), and then it is determined whether the engine is idle by whether the throttle valve is fully closed and the engine speed N is lower than a predetermined speed (S102). . Then, in the case of idling, the ignition timing Ig.T is set to a constant value (T _ID ) (S103), and ignition is executed (S104).

On the other hand, if it is not idle, then it is determined whether or not the load is high depending on whether or not the load T _PK is larger than a predetermined value (T _PK1 ) (S105). Then, if the determination is YES, it means that the load is high, and therefore the coefficient (ALCO) according to the alcohol concentration C is multiplied by the correction amount T _H according to the engine speed N at high load. Thus, the ignition timing correction amount (T _ALCO ) relating to the alcohol concentration is obtained (S106), and the process proceeds to the next step. Here, the coefficient ALCO is obtained from the map for the alcohol concentration C as shown in FIG. 6, and T _H is obtained from the map for the engine speed N shown in FIG. On the other hand, if the determination in S105 is NO, it means that the load is low, so ALCO is multiplied by a fixed advance angle side correction amount T _L to obtain T _ALCO (S107), and the process proceeds to the next step.

In the next step, the final ignition timing Ig.T
_Is added to the basic ignition timing (T _base ) set by the map according to the engine speed N and the load T _PK , and the correction amount (T _W ) according to the water temperature T _HW and T _ALCO obtained in S106 and S107. (S108), and then S10
Ignition is performed at 4.

[0022]

The present invention is configured as described above,
When the alcohol concentration is high, the ignition timing is corrected to the advanced side when the engine speed is low, so that the output and the fuel consumption can be improved without causing knocking.

Further, if the ignition timing is corrected to the retard side when the engine concentration is high and the alcohol concentration is high, knocking can be prevented and the output and fuel consumption can be improved regardless of the engine rotation. it can.

Further, at high load, the ignition timing is corrected to the advance side at low revolutions, and at the time of high rotation is retarded to the advance side, and at low load, the ignition timing is advanced to the advanced side regardless of the engine speed. If the correction is made to, it is possible to prevent knocking regardless of the engine load and improve the output and fuel efficiency.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of the present invention.

FIG. 2 is a diagram showing required ignition timing characteristics of gasoline fuel and alcohol-containing fuel.

FIG. 3 is an overall system diagram of an embodiment of the present invention.

FIG. 4 is a diagram showing a control characteristic in the same embodiment.

FIG. 5 is a flowchart for executing the control of the same embodiment.

FIG. 6 is a characteristic diagram of an alcohol concentration correction coefficient in the same example.

[Explanation of symbols]

1 engine 3 spark plugs 4 Igniter 14 Fuel sensor 17 Control unit

Claims (3)

[Claims] 1. An ignition timing control device for an engine using alcohol-containing fuel, comprising: engine speed detecting means for detecting engine speed; and engine ignition timing based on an output of the engine speed detecting means. On the basis of the outputs of the ignition timing control means for controlling, the alcohol concentration detecting means for detecting the alcohol concentration in the used fuel, the engine speed detecting means and the alcohol concentration detecting means, the alcohol concentration is high at low engine speed. An ignition timing control device for an engine, further comprising an ignition timing correction means for correcting the ignition timing setting by the ignition timing control means to an advance side. 2. The engine ignition according to claim 1, wherein the ignition timing correction means corrects the ignition timing setting by the ignition timing control means to a retard side when the alcohol concentration is high at a high engine speed. Timing control device. 3. An ignition timing control device for an engine using alcohol-containing fuel, comprising: engine speed detecting means for detecting engine speed; and engine ignition timing based on the output of the engine speed detecting means. Ignition timing control means for controlling, load detecting means for detecting engine load, alcohol concentration detecting means for detecting alcohol concentration in fuel used, engine speed detecting means, load detecting means and alcohol concentration detecting means Based on the output, when the load is high, the ignition timing control means corrects the ignition timing setting to the advance side when the alcohol concentration is high at low engine speed, and when the alcohol concentration is high at high engine speed, The ignition timing setting is corrected to the retard side, and when the load is low, the engine speed is An ignition timing control device for an engine, comprising: an ignition timing correction means for correcting the setting of the ignition timing to an advance side when the alcohol concentration is high.