JPH01211627A - Control device for engine - Google Patents

Abstract

PURPOSE:To prevent worsening of combustibility due to a change in an octane number, by a method wherein the octane number of fuel is detected, and according to the detected octane number, an ignition timing and a reflux amount of exhaust gas are controlled. CONSTITUTION:It is detected that a fuel has either a first octane number or a second octane number lower than the first octane number. When it is detected that it has the second octane number, the ignition timing thereof is further delayed than that of the first octane number, and a reflux amount of exhaust gas is decreased. This constitution enables provision of optimum combustion according to the octane number of fuel.

Description

Detailed Description of the Invention (Industrial Application Field) The main purpose of the present invention is to control ignition timing according to the octane number of fuel supplied to an engine, and to improve exhaust gas purification performance. The present invention relates to an engine control device that controls a portion of exhaust gas to be returned to the intake system for recirculation.

(Prior art) An ignition timing control device that aims to suppress the occurrence of knocking in an engine and improve output performance, fuel efficiency, etc. is described in, for example, Japanese Patent Laid-Open No. 60-79167. Based on the detection output obtained from the knock sensor, it is detected whether the fuel supplied to the engine is low octane fuel or high octane fuel, and whether high octane fuel is supplied. When it is detected that fuel with a low octane number has been supplied, the ignition timing is controlled according to the first ignition advance characteristic. It is known that control is performed according to a second ignition advance characteristic that is on the later side of the ignition timing to be controlled.

On the other hand, the exhaust gas emitted from the engine contains components that are not desirable to be released into the atmosphere, and among these components, nitrogen oxides (N.

Component (1) can be reduced by returning a portion of the exhaust gas from the exhaust system to the intake system and refluxing it to lower the combustion temperature of the air-fuel mixture in the combustion chamber. Therefore, in addition to the ignition timing control device as described above, it is generally well known that an engine is provided with an exhaust gas recirculation device that returns exhaust gas from the exhaust system to the intake system for recirculation.

(Problem to be solved by the invention) As described above, detect whether the supplied fuel is a high octane fuel or a low octane fuel, and change the ignition advance characteristic based on the detection result. In an engine equipped with an ignition timing control device and an exhaust gas recirculation device, when a high octane fuel is supplied, the ignition timing is lower than when a low octane fuel is supplied. Since it is set on the forward side,
Although combustibility is increased and output performance is improved, the NOx component in the exhaust gas tends to increase, so it is necessary to increase the amount of exhaust gas recirculation to reduce the NOx component in the exhaust gas. Ru.

Therefore, in such engines, the exhaust! The flow rate is set according to the case where high octane fuel is supplied.

However, if the exhaust recirculation rate is set for when high octane fuel is supplied, the ignition timing will be lower when lower octane fuel is used than when higher octane fuel is supplied. Therefore, the exhaust gas recirculation amount becomes excessive, combustibility deteriorates, and there is a possibility that sufficient output cannot be obtained.

In view of this, the present invention provides for controlling the ignition timing of an engine to which fuel having a first octane number and fuel having a second octane number lower than the first octane number are selectively supplied, depending on the octane number of the fuel. In addition, the octane number of the fuel supplied to the engine has a second octane number. In this case, the amount of exhaust gas recirculated can be made smaller than that in the case where fuel having the first octane number is supplied, thereby avoiding a decrease in flammability and obtaining sufficient output. It is an object of the present invention to provide an engine control device as described above.

(Means for Solving the Problems) In order to achieve the above-mentioned object, an engine control device according to the present invention, as shown in the basic configuration in FIG. a detection means for detecting which of the second octane numbers is lower than the first octane number; an ignition means for igniting the engine; When it is detected that the ignition device has an octane rating, the ignition timing of the ignition means is set to the first
and when it is detected that the ignition device has the second octane number, the ignition timing of the ignition means is controlled to be later than the ignition timing controlled according to the first ignition advance characteristic. In addition to the ignition timing control means for controlling the ignition timing according to the second ignition advance characteristic, and the exhaust gas recirculation means for returning engine exhaust gas to the intake system for recirculation, the exhaust gas recirculation amount control means is provided. The flow control means controls the amount of exhaust gas returned to the intake system by the exhaust gas recirculation means, and the detection means controls the amount of exhaust gas returned to the intake system by the second flow rate control means.
When it is detected that the first octane number is present, less control is performed than when it is detected that the second octane number is the first octane number.

(Function) In the engine control device according to the present invention configured as described above, the ignition timing control means detects that the fuel supplied to the engine by the detection means has the first octane number. If detected, the ignition timing of the ignition means is controlled according to the first ignition advance characteristic;
If it is detected that the ignition means has a second octane number lower than the octane number of The ignition timing is controlled according to the ignition advance characteristics of the fuel, thereby making the ignition timing match the octane number of the fuel.

Further, the exhaust gas recirculation means recirculates the exhaust gas to improve exhaust purification performance, and the exhaust gas recirculation amount control means recirculates the fuel supplied to the engine by the detection means. When it is detected that the exhaust gas has an octane number, the amount of recirculated exhaust gas is determined to be smaller than when it is detected that the exhaust gas has the first octane number. Thereby, when the fuel supplied to the engine has the second octane number, it is possible to avoid a situation where the combustibility deteriorates and the output becomes insufficient.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 shows an example of an engine control device according to the present invention.
It is shown with the main parts of the engine operating with fuel having a first octane rating applied and selectively supplied with fuel having a second octane rating lower than the first octane rating.

In FIG. 2, an engine body 10 having a cylinder head 11 and a cylinder block 12 is equipped with a knocking sensor 15 on the outside to detect the occurrence of knocking, and a cylinder 13 is provided inside. A piston 14 is inserted into the cylinder 13, and an intake passage 20 and an exhaust passage 22 are connected to the cylinder 13, which communicate with each other via an intake valve 16 and an exhaust valve 18. Further, a combustion chamber 24 is formed above the piston 14, and a spark plug 26 is provided adjacent to the combustion chamber 24.

In the intake passage 20, from the upstream side, air filters 28. Air flow meter 29 to detect intake air amount. A throttle valve 30 that opens and closes the intake passage 20 in conjunction with the accelerator pedal. Surge tank 34.
An intake negative pressure sensor 33 and a fuel injection valve 32 that injects fuel pressure-fed from the fuel supply system toward the intake port are provided, and the surge tank 34 is provided with an electromagnetic exhaust recirculation amount adjustment valve 36. It is arranged. The exhaust gas recirculation amount adjustment valve 36 and the exhaust passage 22 communicate with the surge tank 34 and the exhaust passage 22, so that a part of the exhaust gas discharged from the combustion chamber 24 into the exhaust passage 22 is returned to the surge tank 34 and exhausted. Both ends of an exhaust gas recirculation passage 35 for performing recirculation are connected to each other.

Further, a distributor 44 whose rotating shaft is rotationally driven by a crankshaft is attached to the engine main body IO. The distributor 44 is provided with a crank angle sensor 46 that detects the engine speed and crank angle, and is connected to an ignition coil 42 that is integrated with the ignition timing control section 40 . moreover,
In addition to such a configuration, the control unit 100 has (t
It has been done.

The control unit 100 includes an air flow meter 2
A detection signal Sa for detecting the amount of intake air obtained from 9, a detection signal Sb for detecting the negative pressure of intake air obtained from the intake negative pressure sensor 33, and a mechanical detection signal Sb for detecting the negative pressure of the intake air obtained from the knocking sensor 15 due to knocking occurring in the cylinder block 12. a detection signal Sk in which a pulse is formed according to the vibration, and
A detection signal Sn indicating the engine speed and crank angle obtained from the crank angle sensor 46 is supplied, and a water temperature sensor 4 attached to the engine body 10 is supplied.
A detection signal Sw that detects the engine cooling water temperature obtained from 7 is supplied.

The control unit 100 controls fuel injection based on these detection signals, and determines whether the octane number of the fuel supplied to the engine is a first octane number or a second octane number lower than the first octane number. Controls the ignition timing and exhaust gas recirculation amount according to the

When controlling fuel injection by the control unit 100, a detection signal S obtained from the air flow meter 29 is used.
a. Based on the detection signal Sn obtained from the crank angle sensor 46, the detection signal Sw obtained from the water temperature sensor 47, etc., the fuel injection amount for the fuel having the first octane number or the fuel having the second octane number is calculated. An injection drive pulse signal Cp having a pulse width corresponding to the calculated fuel injection amount is formed, and the injection drive pulse signal Cp is supplied to the fuel injection valve 32 at a predetermined timing. Thereby, the fuel injection valve 32 is brought into an open state for a period corresponding to the pulse width of the injection drive pulse signal Cp,
Fuel having a first octane number or a second octane number is injected from the fuel injection valve 32 toward the combustion chamber 24, and the air-fuel ratio of the mixture to be combusted in the combustion chamber 24 is adjusted. It is controlled to a predetermined value.

The control unit 100 stores an ignition advance value according to a first ignition advance characteristic that should be taken when the fuel supplied to the engine has a first octane number, and a second octane number. The ignition advance value according to the second ignition advance characteristic that should be taken when
Each of these is mapped and stored in the built-in memory. In controlling the ignition timing by the control I/roll unit 100, a detection signal Sa obtained from the air flow meter 29 and a detection signal S obtained from the crank angle sensor 46 are used.
Based on n, the detection signal Sw from the water temperature sensor 47, etc., the ignition advance value is first set to follow the first ignition advance characteristic, and the ignition is controlled at a timing corresponding to the set ignition advance value. The signal Cq is supplied to an ignition timing control section 40 provided in an ignition coil 42. Thereby,
A secondary high voltage pulse is obtained from the ignition coil 42 and supplied to the ignition plug 26 via the distributor 44,
The spark plug 26 performs ignition with a set ignition advance value.

Under such circumstances, the detection signal S from the knocking sensor 15
Depending on the degree of occurrence of knocking detected based on k,
the fuel supplied to the engine has a first octane rating, or;

It is determined whether it has the second octane rating.

As a result, if the fuel supplied to the engine has the second octane rating, the ignition advance value is changed to one that follows the second ignition advance characteristic.

Furthermore, in the control unit 100, when the fuel supplied to the engine has the first octane number, the amount of intake air to be recirculated, the engine rotation speed, the engine cooling water temperature, etc. The first exhaust gas recirculation amount, and the first exhaust gas recirculation amount that changes depending on the intake air amount, engine rotation speed, engine cooling water temperature, etc. that should be recirculated in the case of having a second octane number. The second, smaller exhaust gas recirculation amounts are also mapped and stored in the built-in memory. In controlling the original amount of exhaust gas recirculation performed by the control unit 100, the detection signal S
First, a first exhaust gas recirculation amount is set based on a, Sn, Sw, etc., and a control pulse signal Ce corresponding to the set first exhaust gas recirculation amount is applied to the exhaust gas recirculation amount adjustment valve 36 for each cycle.
As a result, the exhaust gas recirculation amount adjustment valve 36 is kept open for a period corresponding to the pulse width of the control pulse signal Ce, and the exhaust gas from the exhaust passage 22 reaches the set first exhaust gas recirculation amount. is supplied to the surge tank 34.

Under such circumstances, the detection signal S from the knocking sensor 15
Depending on the degree of occurrence of knocking detected based on k,
It is determined whether the fuel supplied to the engine has a first octane number or a second octane number, and as a result, the fuel supplied to the engine has a second octane number. , a second exhaust recirculation amount is set in place of the first exhaust recirculation amount based on the detection signals Sa, Sn, Sw, etc., and the second exhaust recirculation amount is set according to the set second exhaust recirculation amount. The control pulse signal Ce is supplied to the exhaust gas recirculation amount regulating valve 36 for each cycle, and the exhaust gas recirculation amount regulating valve 36 is thereby kept open for a period corresponding to the pulse width of the control pulse signal Ce. The exhaust gas from 22 is smaller than the first exhaust gas recirculation amount.
is supplied to the surge tank 34 with an exhaust gas recirculation amount of .

In addition, the exhaust gas recirculation in which the amount of exhaust gas recirculation is controlled is as follows:
This is not performed when the engine load indicated by the detection signal sb is high or extremely low.

By controlling the ignition timing and the amount of exhaust gas recirculation as described above, the fuel supplied to the engine has the first octane number and the second octane number. Ignition is performed with appropriate ignition timing according to the octane number of the fuel, and the output performance of the engine is improved. Since the amount of exhaust gas recirculation is reduced compared to a certain amount, the operational performance of the engine is not impaired by the exhaust gas recirculation, and the NOx component in the exhaust gas can be reduced.

The control unit 100 that performs the above-described control is configured using, for example, a microcomputer, and an example of a program executed by the microcomputer in such a case to control the ignition timing and the amount of exhaust gas recirculation is as follows. , will be explained with reference to the flowchart in FIG.

In the program shown in the flowchart of FIG. 3, for example, the program starts when the ignition switch is turned on, and after the start, the detection signals Sa, Sb, Sn, and Sw are taken in in process 101, and in the next process 102. , the intake air amount, engine rotation speed, and engine cooling water temperature detected by the detection signals Sa, Sn, and Sw, among the ignition advance values according to the first ignition advance characteristics mapped and stored in the built-in memory. The target ignition advance value θ8 corresponding to the fuel having the first oclotane number is selected by selecting the one determined according to A target corresponding to the fuel having the first octane number is selected from the exhaust gas recirculation amount, which is determined according to the intake air amount generated by the detection signals Sa, Sn, and Sw, the engine rotation speed, and the engine cooling water temperature. The process 104 is performed by setting the exhaust gas recirculation amount E.
Proceed to. In process 104, the ignition timing is controlled so that the actual ignition advance value becomes equal to the target ignition advance value θ, and further in process 105, the detection signal s
The target exhaust gas recirculation amount E is the actual exhaust gas recirculation amount under the state in which exhaust gas recirculation is to be performed, which is set according to the intake negative pressure created in b.

The amount of exhaust gas recirculation is controlled so that

Then, in the process 106, the process 107 detects the f number Sk and proceeds to the decision 107.
, it is determined based on the detection signal Sk whether knocking is occurring in the engine to a predetermined degree or higher. In such a case, the ignition timing is controlled in the process 104 so that the ignition advance value becomes the target ignition advance value θ corresponding to the fuel having the first octane number set in the process 102. If the fuel supplied to the engine has the first octane number, knocking will not occur or will occur to a less than a predetermined degree; If it has an octane number of 2, knocking will occur to a predetermined degree or higher. Therefore, if the degree of occurrence of knocking is not above a predetermined level, the fuel supplied to the engine is assumed to have the first octane number and returns to the original value, and
If the degree of occurrence of knocking is equal to or higher than a predetermined value, it is assumed that the octane number of the fuel supplied to the engine has the second octane number, and the process proceeds to process 108.

In process 108, the detection signals Sa, Sb, Sn, and Sw are taken in as in process 101, and in the subsequent process 109, they are determined to be on the lag side with respect to the first ignition advance characteristic mapped and stored in the built-in memory. Of the ignition advance values according to the second ignition advance characteristic, the detection signal Sa,
A target ignition advance value θ1 corresponding to the fuel having the second octane number is set by selecting the intake air amount generated by Sn and Sw, the engine rotation speed, and the engine cooling water temperature, and then Then, in process 110, the amount of intake air generated by the detection signals Sa, Sn, and Sw out of the second exhaust gas recirculation amount that is smaller than the first exhaust gas recirculation amount mapped and stored in the built-in memory. , the target exhaust recirculation amount Et corresponding to the fuel having the second octane number is set, and the process 111
Proceed to. In process 111, the ignition timing is controlled so that the actual ignition advance value becomes the target ignition advance value θ1, and further, in process 112, the detection signal s
The exhaust gas recirculation amount is controlled so that the actual exhaust gas recirculation amount becomes the target exhaust recirculation amount EL under the condition in which exhaust gas recirculation is to be performed, which is set according to the intake negative pressure generated in b. and returns to process 108.

In the above example, whether the fuel supplied to the engine has the first octane number or the second octane number is detected based on the degree of occurrence of knocking. However, it is not limited to that,
The fuel supplied to the engine has a first octane rating and a second octane rating.
Which of the octane numbers does it have?
For example, detection may be performed based on a difference in specific gravity or the like.

(Effects of the Invention) As is clear from the above description, according to the engine control device according to the present invention, the fuel supplied to the engine has a first octane number and a second octane number lower than the first octane number. It is detected whether the
Since the ignition timing is controlled to follow the ignition advance characteristic according to the detected octane number of the fuel and combustibility is improved, output performance can be improved. Furthermore, since the exhaust gas is recirculated, the exhaust gas purification performance can also be improved. Further, if it is detected that the octane number of the fuel supplied to the engine is of a second octane number, the amount of exhaust gas recirculation is compared to that of the first octane number. By performing the control to reduce the amount of exhaust gas, the exhaust gas can be purified without impairing the driving performance.

[Brief explanation of the drawing]

FIG. 1 is a basic configuration diagram showing an engine control device according to the present invention in accordance with the claims, and FIG. FIG. 3 is a flowchart showing an example of a program executed by a microcomputer used in the control unit provided in the example shown in FIG. In the figure, 10 is the engine body, 15 is a knocking sensor,
26 is a spark plug, 32 is a fuel injection valve, 35 is an exhaust gas recirculation passage, 36 is an exhaust gas recirculation amount adjustment valve, 40 is an ignition timing control section, 42 is an ignition coil, 44 is a distributor, 46
1 is a crank angle sensor, and 100 is a control unit.

Claims (1)

[Scope of Claims] Detection means for detecting whether fuel supplied to the engine has a first octane number or a second octane number lower than the first octane number; and ignition for the engine. and when the detection means detects that the fuel has a first octane number, the ignition timing of the ignition means is controlled according to a first ignition advance characteristic; , when the detection means detects that the fuel has the second octane number, the ignition timing of the ignition means is set to a position later than the ignition timing controlled according to the first ignition advance characteristic. ignition timing control means for controlling the ignition timing according to a second ignition advance characteristic; exhaust gas recirculation means for returning and recirculating the exhaust gas of the engine to the intake system; and exhaust gas being returned to the intake system by the exhaust gas recirculation means. when the detection means detects that the fuel has a second octane number, compared to when it detects that the fuel has a first octane number; An engine control device comprising: a small amount of exhaust gas recirculation amount control means;