JP3572873B2 - Control device for internal combustion engine - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a control device for an internal combustion engine of an automobile or the like, and more particularly to a control device for an internal combustion engine capable of burning a rare air-fuel ratio by stratifying supply fuel.
[0002]
[Prior art]
In an internal combustion engine provided with a fuel injection valve that injects fuel directly into a cylinder, when a torque reduction is required at the time of shifting of an automatic transmission or the like, for example, as disclosed in Japanese Patent Application Laid-Open No. 4-301153, A control device for an internal combustion engine that realizes torque reduction by delaying the injection timing from a direct injection type fuel injection valve so that thermal efficiency deteriorates, and aims to reduce the fuel supply amount to dilute the mixture to reduce the torque. Methods are known.
[0003]
[Problems to be solved by the invention]
However, in such a conventional control method for an internal combustion engine in which the torque is changed according to the fuel injection timing, in order to improve the fuel efficiency by realizing a lean air-fuel ratio by stratified combustion, if the injection timing is largely changed, the combustible air-fuel mixture is changed to the ignition plug Since the sparks fly after passing through the position, the combustion state deteriorates or misfires occur, and there is a possibility that the operating characteristics and the exhaust characteristics may be reduced. Also, in stratified charge combustion, since the air-fuel mixture is preliminarily diluted to near the limit at which combustion becomes unstable in order to improve fuel efficiency, even when the torque is reduced by such a lean air-fuel mixture, the combustion state still remains. This method has a problem that the operating characteristics and the exhaust characteristics are liable to be deteriorated even in this method because the deterioration is caused more than desired or a misfire occurs.
[0004]
SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has as its object the purpose of making a request for a torque reduction in the internal combustion engine, even if the ignition timing is delayed from a normal timing. It is an object of the present invention to provide a control device for an internal combustion engine that can reliably ignite with a spark plug close to a lump and, as a result, significantly improve the operating characteristics and exhaust characteristics of the internal combustion engine, which aims to improve fuel efficiency by stratified combustion. Is what you do.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, a vortex is formed in a combustion chamber in an intake stroke, a combustible mixture is formed in a specific region in the combustion chamber, and the combustible mixture is ignited by a spark plug. the control apparatus for an internal combustion engine realizing the lean burn by a torque change instruction means for instructing a change to the current engine torque, combustible at the ignition timing of the normal is disposed in the moving path of the combustible mixture in the combustion chamber A first ignition plug arranged at a position where the mixture reaches the periphery, and a ignition timing at a predetermined retarded timing from the regular ignition timing on a combustible mixture movement path downstream of the first ignition plug . a second spark plug combustible mixture is placed in a position to reach the neighborhood, the ignition timing when the engine torque in response to the torque change instructing means is changed to a less than the current value the value current Ignition timing setting means for delaying the ignition timing from the current value in accordance with the torque instruction value or, when the engine torque is changed to a value higher than the current value, causing the ignition timing to advance from the current value in accordance with the torque instruction value; Spark plug selection means for selecting the first spark plug when the ignition timing set by the setting means is on the advance side of the predetermined ignition timing, and selecting the second spark plug when the ignition timing is on the retard side ; , Is characterized by the following.
[0006]
Embodiments of the present invention
Hereinafter, the present invention will be described in detail based on an embodiment of the invention shown in the accompanying drawings.
[0007]
FIG. 1 is a diagram showing a basic configuration of an engine to which a control device according to the present embodiment is applied. In the figure, reference numeral 1 denotes a fuel injection valve, reference numeral 2 denotes a cylinder wall surface, and reference numeral 3 denotes a control valve. Reference numerals 4 and 5 denote intake pipes, reference numeral 6 denotes an intake valve, reference numeral 7 denotes a combustible mixture, reference numeral 8 denotes an exhaust pipe, reference numeral 9 denotes an exhaust valve, reference numeral 10 denotes a first spark plug, Reference numeral 11 indicates a second spark plug. FIG. 2 is a cross-sectional view taken along the line XX of FIG. 1 showing a concave portion 12 formed for forming a vortex flow of the piston.
[0008]
Next, the operation of the engine having the above configuration will be described.
[0009]
The relationship shown in FIG. 3 exists between the ignition timing and the “indicated average effective pressure P _i ” that is the torque generated by combustion.
[0010]
Normal, i.e., in the state of an ignition timing which gives the best point of thermal efficiency, as shown in FIG. 4, cylinder pressure maximum timing theta _pmax is a predetermined target _value: such that (theta _{targ MBT} or Notsuku limit point), the ignition The timing and the fuel injection timing are set with respect to the position of the first spark plug 10.
[0011]
The “indicated average effective pressure P _i ” is obtained by integrating the in-cylinder pressure P _cyl and the volume change rate dV shown in FIG. 4 over one cycle, and dividing the result by the stroke volume.
[0012]
If the peak timing of the in-cylinder pressure P _cyl shifts later and the peak value decreases, the generated torque decreases. Therefore, in general, the peak position of the in-cylinder pressure P _cyl and the indicated mean effective pressure P _i have a relationship as shown in FIG. become.
[0013]
Therefore, if the peak timing of the in-cylinder pressure P _cyl is changed by controlling the fuel injection timing and the ignition timing, it is possible to reduce the torque without changing the air-fuel ratio. Since the injection timing and the ignition timing can be changed for each combustion, it is possible to realize a torque change with extremely good responsiveness.
[0014]
As an advantage of performing such stratified combustion, there is a significant improvement in fuel efficiency due to a lean air-fuel ratio. In the internal combustion engine shown in FIG. 1, the mode is switched between stratified combustion and homogeneous combustion depending on the operation state.
[0015]
For example, the control valve 3 is fully open during homogeneous combustion, but is fully closed during stratified combustion. At this time, since the intake air is sucked into the combustion chamber only from the intake pipe 5, a counterclockwise vortex flows in a half of the combustion chamber on the intake valve 6 side in cooperation with the effect of the concave portion 12 provided in the piston. Are formed in a plane perpendicular to the direction of piston movement.
[0016]
When this vortex is formed, when fuel is injected from the fuel injection valve 1, a combustible mixture mass 7, which is a ignitable rich mixture mass, is formed, and the combustible mixture mass 7 moves on the vortex. .
[0017]
In order to achieve good combustion in an engine that performs stratified combustion, it is necessary to ignite when the combustible mixture 7 reaches the vicinity of the spark plug. Now, it is assumed that the fuel injection timing is constant. In a normal engine, the ignition plug is arranged such that the combustible mixture 7 just reaches the periphery of the ignition plug at the regular ignition timing. Therefore, if an attempt is made to respond to the torque-down request by delaying the ignition timing more than the normal ignition timing, the combustible mixed air mass 7 may pass around the periphery of the ignition, and may not be reliably burned.
[0018]
In this embodiment, on the other hand, the first spark plug 10 corresponding to the normal ignition timing and the second spark plug 11 are disposed at a position where the combustible mixture 7 passes later than that. Therefore, even if the ignition timing is delayed later than normal, it is possible to reliably ignite the combustible mixed air mass 7.
[0019]
5 and 6 are block diagrams showing a basic configuration of a control device for realizing this. In FIG. 5, reference numeral 21 denotes torque change instructing means, reference numeral 22 denotes ignition timing setting means, and reference numeral 23 is an ignition plug selection means, 24 is an ignition coil, 25 is an ignition circuit, 26 is a plug changeover switch, 27 is an ignition switch, 28 is a battery, 29 is a crank angle sensor. Each is shown.
[0020]
That is, the torque change instruction means 21 is started at the start of one cycle of the engine, inputs an engine operation state signal such as a throttle opening and a shift signal of a torque converter, and an operation state signal of a transmission, and detects a change in torque. It is to calculate.
[0021]
Further, the ignition plug selecting means 23, depending on the setting of the ignition timing T, the ignition of the first spark plug 10 if the ignition timing T is long as the advanced less than the predetermined value T _O which is set in advance circuit 25 connected to the ignition timing T is equal to or a predetermined value T _O, or, when larger (retard), connects the second spark plug 11 to the ignition circuit 25.
[0022]
Actually, the plug changeover switch 26 is configured as an electric switch circuit such as a transistor, and the first ignition plug 10 and the second ignition plug 11 And. The predetermined value To is set in advance according to the speed of the vortex, the distance between the first spark plug 10 and the second spark plug 11, the amount of fuel to be injected, and the like.
[0023]
The ignition timing setting means 22 calculates the ignition timing T by inputting the torque change. This ignition timing T can be stored in advance as a map for the amount of change in torque.
[0024]
That is, the ignition timing T is compared with the crank angle signal, and the ignition switch 27 is turned on and off when the crank angle matches the ignition timing T. Actually, the ignition switch 27 is configured as an electric switch circuit such as a transistor, and the ignition plug 10.11 is turned on by the ignition plug 10.11 in accordance with the ON / OFF signal of the ignition switch of the injection timing setting means (not shown). The first spark plug 10 or the second spark plug 11 is connected to the battery 28 via 25, and sparks are generated.
[0025]
In the above description, an engine in which a vortex is formed in a direction perpendicular to the piston movement surface has been described as an example. For example, in a tumble vortex type internal combustion engine in which a vortex is formed in a plane in the piston movement direction, the first is As shown in FIGS. 7 and 8, the ignition plug 10 and the second ignition plug 11 may be arranged on a curve where the cross section of the cylinder head and the surface on which the vortex is formed intersects. In this embodiment, the same components as those in the embodiment shown in FIGS. 1 to 6 are denoted by the same reference numerals in FIGS. 7 and 8 as those in the embodiment shown in FIGS. The detailed description is omitted here.
[0026]
【The invention's effect】
As described above, in the control device for an internal combustion engine according to the present invention, in the internal combustion engine that aims to improve fuel efficiency by stratified combustion, when a request for changing the torque occurs, the ignition timing is delayed from the normal timing. Can reliably ignite with an ignition plug close to the combustible air-fuel mass, so that it is possible to greatly improve the operating characteristics and exhaust characteristics of the internal combustion engine, which aims to improve fuel efficiency by stratified combustion. Can be
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a basic configuration of an engine to which a control device according to an embodiment of the present invention is applied;
FIG. 2 is a sectional view taken along line XX of FIG. 1;
FIG. 3 is a graph showing a relationship between an indicated average effective pressure and an ignition timing by the control device.
FIG. 4 is a graph showing a relationship among a cylinder pressure change, a volume change rate, and a crank angle by the control device.
FIG. 5 is a block diagram illustrating a basic configuration of a control device according to an embodiment of the present invention.
FIG. 6 is a flowchart showing an example of control steps of the control device.
FIG. 7 is an explanatory diagram showing the arrangement of spark plugs when the present invention is applied to a tumble swirl type engine.
FIG. 8 is an explanatory sectional view taken along line XX of FIG. 7;
[Explanation of symbols]
REFERENCE SIGNS LIST 1 fuel injection valves 4, 5 intake pipe 7 combustible mixed air mass 8 exhaust pipe 10 first ignition plug 11 second ignition plug 21 torque change instructing means 22 ignition timing setting means 23 ignition plug selecting means 25 ignition circuit 26 plug switching Switch 27 ignition switch 28 battery 29 crank angle sensor

Claims (1)

A control device for an internal combustion engine that forms a vortex in a combustion chamber in an intake stroke, forms a combustible mixture in a specific region in the combustion chamber, and ignites the combustible mixture with a spark plug to realize lean combustion, A torque change instructing means for instructing a change in the current engine torque; and a first torque change instructing means arranged on a movement path of the combustible mixture in the combustion chamber and arranged at a position where the combustible mixture reaches the periphery at a regular ignition timing. And at a position where the combustible mixture reaches the periphery at a predetermined retarded ignition timing from the regular ignition timing on a combustible mixture moving path downstream of the first ignition plug . and 2 of the ignition plug, delayed in accordance with the torque instruction value from the current value of the ignition timing when the engine torque in response to the torque change instructing means is changed to a less than the current value value, or, e And ignition timing setting means for advancing in accordance with the torque instruction value from the current value ignition timing when Jintoruku is changed to a higher value than the current value, the ignition timing set by the ignition timing setting means than the predetermined ignition timing And a spark plug selecting means for selecting a first spark plug when the engine is on the advance side and selecting a second spark plug when the engine is on the retard side. .

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