JPH112172A - Control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for an internal combustion engine in which it can be surely ignited by a spark plug close to a combustible mixed gas block even when an ignition timing is delayed from a regular timing in the case where demand for torque-down is generated. SOLUTION: A control device comprises a torque change instruction means 21 to instruct change of an engine torque to the internal combustion engine in which combustible mixed gas is formed in a specific zone in a combustion chamber in an intake stroke to be ignited by a spark plug to realize lean burn, a first spark plug 10 disposed in a moving passage of the combustible mixed gas in the combustion chamber to be used for ignition at a regular ignition timing, plural spark plugs 11 disposed in order in the moving passage downstream of the first spark plug, an ignition timing setting means 22 to change an ignition timing when the engine torque is changed from a current value by the torque change instruction means 21, and a spark plug selecting means 23 to select spark for ignition in accordance with a torque instruction value by the ignition timing setting means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. 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 performing a rare air / fuel ratio combustion by stratifying supply fuel.

[0002]

2. Description of the Related Art In an internal combustion engine provided with a fuel injection valve for injecting fuel directly into a cylinder, when a torque reduction is required at the time of shifting of an automatic transmission, for example, Japanese Patent Laid-Open No.
As disclosed in Japanese Patent Publication No. 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 as to deteriorate thermal efficiency, or by reducing a fuel supply amount. 2. Description of the Related Art A method for reducing the torque by diluting an air-fuel mixture is known.

[0003]

However, in such a conventional control method of an internal combustion engine in which the torque is changed by the fuel injection timing, when the fuel efficiency is improved by realizing a lean air-fuel ratio by stratified charge combustion, the injection timing must be reduced. If a large change is made, the sparks will fly after the combustible mixture has passed the position of the ignition plug, so that the combustion state will be deteriorated or misfired, and there has been a risk that the operating characteristics and exhaust characteristics will be reduced. . Further, 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 may occur more than desired or a misfire may occur.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to make it possible to reduce the ignition timing even if the request for torque reduction in the internal combustion engine is made later than the normal timing. A control device for an internal combustion engine that can reliably ignite with an ignition plug close to a combustible mixed air mass and, as a result, significantly improve the operating characteristics and exhaust characteristics of the internal combustion engine that improves fuel efficiency by stratified combustion. It is something to offer.

[0005]

In order to achieve the above object, according to the present invention, a vortex is formed in a combustion chamber during an intake stroke, and a combustible air-fuel mixture is formed in a specific region in the combustion chamber. Torque change instructing means for instructing the internal combustion engine that realizes lean combustion by igniting the combustible air-fuel mixture with an ignition plug to change the current engine torque;
A first spark plug arranged on a movement path of the combustible mixture in the combustion chamber and used for ignition at a normal ignition timing; and a plurality of ignition plugs arranged in order on a movement path downstream of the first ignition plug. When the engine torque is changed to a value lower than the current value according to the torque change instruction means, the ignition timing is delayed from the current value according to the torque instruction value, or the engine torque is changed to a value higher than the current value. When the ignition timing is set, the ignition timing is advanced from the current value according to the torque instruction value, and the ignition plug selection means is used to select an ignition plug that ignites according to the torque instruction value by the ignition timing setting means. A control device having the above configuration is provided.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on an embodiment of the invention shown in the accompanying drawings.

FIG. 1 is a diagram showing a basic configuration of an engine to which a control device according to this embodiment is applied. In FIG. 1, reference numeral 1 denotes a fuel injection valve, reference numeral 2 denotes a cylinder wall surface, and reference numeral 3 denotes a cylinder wall. Control valves, reference numerals 4 and 5 indicate intake pipes, reference numeral 6 indicates intake valves,
Reference numeral 7 denotes a combustible mixed air mass, reference numeral 8 denotes an exhaust pipe, reference numeral 9 denotes an exhaust valve, reference numeral 10 denotes a first spark plug, and reference numeral 11 denotes a second spark plug. FIG. 2 is a sectional view taken along the line XX of FIG. 1 showing a concave portion 12 formed for forming a vortex flow of the piston.

Next, the operation of the engine having the above configuration will be described.

FIG. 3 shows a relationship between the ignition timing and the "indicated average effective pressure P _i " which is a torque generated by combustion.

In the normal state, that is, in the state of the ignition timing giving the best point of the thermal efficiency, as shown in FIG.
_pmax is a predetermined target value (θ _targ: MBT or Notsuku limit point)
The ignition timing and the fuel injection timing are set with respect to the position of the first spark plug 10 so that

[0011] The "indicated average effective pressure P _i " is
It 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] residual values decrease peak shifted later time peak cylinder pressure P _cyl, the generation torque is reduced, in general the peak position of the in-cylinder pressure P _cyl in the indicated mean effective pressure P _i shown in FIG. 3 It becomes such a relationship.

Therefore, by controlling the fuel injection timing and the ignition timing to change the peak timing of the in-cylinder pressure P _cyl ,
The torque can be reduced 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.

An advantage of performing such stratified combustion is that the fuel efficiency is greatly improved by making the air-fuel ratio lean. In the internal combustion engine shown in FIG. 1, the operation mode is switched between stratified combustion and homogeneous combustion.

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.

When the fuel is injected from the fuel injection valve 1 when the vortex is formed, a combustible mixture mass 7 which is a ignitable rich mixture mass is formed, and the combustible mixture mass 7 is formed.
Moves in a swirl.

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 regular ignition timing, the combustible mixed air mass 7 may pass around the periphery of the ignition, and may not be reliably burned.

In this embodiment, on the other hand, the first spark plug 10 corresponding to the normal ignition timing and the second spark plug 11 at a position where the combustible mixed air mass 7 passes at a time later than the first spark plug 10 are connected. Since it is provided, even if the ignition timing is delayed than normal, it is possible to reliably ignite the combustible mixed air mass 7.

FIGS. 5 and 6 are block diagrams showing the basic configuration of a control device for realizing this. In FIG.
Reference numeral 21 denotes torque change instructing means, reference numeral 22 denotes ignition timing setting means, reference numeral 23 denotes spark plug selection means, and reference numeral 2 denotes
Reference numeral 4 denotes an ignition coil, reference numeral 25 denotes an ignition circuit, reference numeral 26 denotes a plug changeover switch, reference numeral 27 denotes an ignition switch, reference numeral 28 denotes a battery, and reference numeral 29 denotes a crank angle sensor.

That is, the torque change instructing means 21 is started at the start of one cycle of the engine, inputs an engine operating state signal such as a throttle opening and a shift signal of a torque converter, and an operating state signal of a transmission, and receives the torque. The change is calculated.

The ignition plug selection means 23 activates the first ignition plug 10 if the ignition timing T is advanced smaller than a predetermined value T _O according to the setting of the ignition timing T. The second spark plug 11 is connected to the ignition circuit 25 when the ignition timing T is equal to or greater than the predetermined value T _O (retarded).

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 The ignition plug 11 is switched. 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.

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.

That is, the ignition timing T is compared with a crank angle signal, and when the crank angle matches the ignition timing T, the ignition switch 27 is turned on and off. Actually, the ignition switch 27 is configured as an electric switch circuit such as a transistor, and the injection timing setting means (not shown)
The ignition plug 10.11 is connected to the battery 28 via the ignition circuit 25 in response to the ON-OFF signal of the ignition switch of the first ignition plug 10 or the second ignition plug 11
Sparks.

In the above description, an engine in which a vortex is formed in a direction perpendicular to the piston movement plane has been described as an example. For example, in a tumble vortex internal combustion engine in which a vortex is formed in a plane in the piston movement direction, , First spark plug 10
The second spark plug 11 and the second spark plug 11 may be arranged in a curved line where the cross section of the cylinder head crosses the surface where the vortex is formed, as shown in FIGS. 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]

As described above, in the control apparatus for an internal combustion engine according to the present invention, in the internal combustion engine aiming at improvement of fuel efficiency by stratified combustion, when a request for changing the torque occurs, the ignition timing is adjusted to the normal value. Even if it is later than the timing, it is possible to reliably ignite with an ignition plug close to the combustible mixed air mass, so that it is possible to greatly improve the operating characteristics and exhaust characteristics of the internal combustion engine aiming to improve fuel efficiency by stratified combustion. Excellent effects can be obtained.

[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 the 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 an arrangement state of a spark plug 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;

DESCRIPTION OF SYMBOLS 1 Fuel injection valve 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 switch 27 Ignition switch 28 Battery 29 Crank angle sensor

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02B 23/10 F02B 23/10 DM F02D 29/00 F02D 29/00 C 41/02 325 41/02 325E F02M 61/14 310 F02M 61/14 310S F02P 5/15 F02P 5/15 B

Claims (1)

[Claims] 1. A vortex is formed in a combustion chamber during an intake stroke, and a combustible air-fuel mixture is formed in a specific region in the combustion chamber.
Torque change instructing means for instructing a control device for an internal combustion engine that realizes lean combustion by igniting this combustible air-fuel mixture with a spark plug, to change the current engine torque;
A first spark plug arranged on a movement path of the combustible mixture in the combustion chamber and used for ignition at a normal ignition timing; and a plurality of ignition plugs arranged in order on a movement path downstream of the first ignition plug. When the engine torque is changed to a value lower than the current value according to the torque change instruction means, the ignition timing is delayed from the current value according to the torque instruction value, or the ignition torque is changed to a value higher than the current value. Ignition timing setting means for increasing the ignition timing in accordance with the torque instruction value from the current value, and ignition plug selection means for selecting ignition to fire in accordance with the torque instruction value by the ignition timing setting means. A control device for an internal combustion engine, comprising: