JP2011144721A - Ignition timing control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ignition timing control device of an internal combustion engine, properly correcting ignition timing even when varying basic ignition timing for idling, and enhancing the stability of idling irrespectively of cold time and warm time. <P>SOLUTION: An amount of ignition retard from the base ignition timing for idling is acquired (150). A momentarily-varying rotation speed of engine rotation speed during idling is acquired (140). By using a momentarily-varying rotation speed correction amount (160), which becomes larger to a retard side according as the momentarily-varying rotation speed becomes larger to a plus side, and which becomes larger to an advance side according as the momentarily-varying rotation speed becomes larger to a minus side, and an ignition retard amount correction factor (170) which reduces the momentarily-varying rotation speed correction amount according as the ignition retard amount becomes larger, a correction amount of ignition timing for decreasing the momentarily-varying rotation speed is calculated (180). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an ignition timing control device for an internal combustion engine, and more particularly to an ignition timing control device for an internal combustion engine suitable for executing ignition timing control for an internal combustion engine mounted on a vehicle.

  Conventionally, as disclosed in, for example, Patent Document 1, an internal combustion engine capable of advancing and retarding ignition timing is known. Further, in this publication, the engine speed is detected during idling, the ignition timing is retarded if the engine speed is higher than the target speed, and the ignition timing is advanced if the engine speed is lower than the target speed. Control of ignition timing is disclosed. According to such control, idling can be stabilized.

JP-A-6-137243 Japanese Utility Model Publication No. 3-51179 JP 2004-36570 A JP 2009-7993 A JP 2007-177739 A JP 2009-24684 A

  Incidentally, in the torque characteristic with respect to the ignition timing, the amount of torque change with respect to the amount of change in ignition timing increases as the ignition timing is retarded (FIG. 19). Therefore, in the conventional internal combustion engine, when control is performed to retard the reference ignition timing at the time of cold idling from that at the time of warm idling in order to improve emissions, the torque with respect to the change amount of the ignition timing The amount of change is greater during cold than during warm. Therefore, if the conventional ignition timing is controlled as in the warm state, the torque changes greatly and overcorrection can occur. For this reason, there is a risk of deteriorating the idle stability.

  The present invention has been made to solve the above-described problems, and even when the ignition timing of the idle reference is changed, the ignition timing is appropriately corrected, regardless of whether it is cold or warm. It is an object of the present invention to provide an ignition timing control device for an internal combustion engine capable of improving idle stability.

In order to achieve the above object, a first invention is an ignition timing control device for an internal combustion engine,
Ignition retard amount acquisition means for acquiring an ignition delay amount from the base ignition timing of the idle;
Instantaneous fluctuation speed acquisition means for acquiring the instantaneous fluctuation speed of the engine speed during idling;
The larger the instantaneous fluctuation rotational speed is on the plus side, the larger the retarding speed side is. The larger the instantaneous fluctuation rotational speed is on the negative side, the larger the instantaneous fluctuation rotational speed is. Ignition timing correction amount calculating means for calculating a correction amount of the ignition timing for reducing the instantaneous variable rotational speed using an ignition delay amount correction coefficient that decreases the instantaneous variable rotational speed correction amount. It is characterized by that.

The second invention is the first invention, wherein
A concentration acquisition means for acquiring the ethanol concentration in the fuel;
The ignition timing correction amount calculation means uses the instantaneous variation rotational speed correction amount, the ignition delay amount correction coefficient, and an ethanol concentration correction coefficient that increases the instantaneous variable rotational speed correction amount as the ethanol concentration increases. And calculating the correction amount of the ignition timing.

The third invention is the first or second invention, wherein
A load factor acquisition means for acquiring an engine load factor;
The ignition timing correction amount calculating means includes the instantaneous variation rotational speed correction amount, the ignition delay amount correction coefficient, and an engine load factor correction coefficient that decreases the instantaneous variable rotational speed correction amount as the engine load factor increases. And calculating a correction amount of the ignition timing.

According to a fourth invention, in any one of the first to third inventions,
A concentration acquisition means for acquiring the ethanol concentration in the fuel;
A load factor acquisition means for acquiring an engine load factor;
Guard setting means for setting the upper limit advance amount before the top dead center of the ignition timing to the delay side as the engine load factor and ethanol concentration are higher,
An ignition timing changing means for changing the final ignition timing to the upper limit advance amount when the ignition timing corrected using the correction amount becomes larger than the upper limit advance amount; It is characterized by providing.

According to a fifth invention, in any one of the first to fourth inventions,
The internal combustion engine
A mechanism for variably setting a working angle and a lift amount of the intake valve, and a variable valve mechanism that reduces the lift amount as the working angle is decreased;
An intake valve delay opening control means for driving the variable valve mechanism to change the opening timing of the intake valve to a timing delayed from the top dead center of the intake stroke;
The ignition timing correction amount calculation means is configured to correct the instantaneous fluctuation rotational speed correction amount according to the instantaneous fluctuation rotational speed correction amount, the ignition delay amount correction coefficient, and the valve opening timing changed by the intake valve delay opening control means. The correction amount of the ignition timing is calculated using an intake valve delay opening correction coefficient for correcting the amount.

According to a sixth invention, in any one of the first to fifth inventions,
Base ignition timing correction means for correcting the base ignition timing to the retard side as the required ignition timing corresponding to the operating state is retarded is provided.

  As torque characteristics with respect to the ignition timing, the amount of torque change with respect to the amount of change in ignition timing increases as the ignition timing retards, that is, as the ignition delay amount increases. Therefore, in the first aspect of the invention, the ignition timing correction amount that reduces the instantaneous variation rotational speed correction amount as the ignition retardation amount increases is calculated. By decreasing the instantaneous fluctuation rotational speed correction amount as the ignition delay amount is larger, the change amount of the ignition timing can be reduced and the torque change amount can be reduced as the retard angle side. Therefore, according to the present invention, even when the ignition timing is greatly retarded during idling, it can be corrected to an appropriate ignition timing, and the idling stability can be enhanced regardless of whether it is cold or warm.

  The higher the ethanol concentration in the fuel, the faster the combustion rate. For this reason, the higher the ethanol concentration, the smaller the torque change amount with respect to the ignition timing change amount. According to the second invention, the instantaneous fluctuation rotational speed correction amount is increased as the ethanol concentration is higher. For this reason, according to this invention, even if it is a case where ethanol concentration changes, stability of an idle can be improved.

  The higher the engine load factor, the greater the torque change amount with respect to the ignition timing change amount. According to the third aspect of the invention, the instantaneous variation rotational speed correction amount is decreased as the engine load factor is higher. For this reason, according to this invention, even if it is a case where an engine load factor changes, stability of an idle can be improved.

  The higher the engine load factor and ethanol concentration, the faster the required advance angle. According to the fourth aspect of the invention, the higher the engine load factor and the ethanol concentration, the higher the upper limit advance amount before the top dead center of the ignition timing is set on the delay side. Therefore, according to the present invention, even when the engine load factor and the ethanol concentration are high, knocking can be suppressed and idle stability can be enhanced.

  According to the fifth aspect of the present invention, even when the intake valve slow opening control is performed, the instantaneous variation rotational speed correction amount can be appropriately corrected to improve the idle stability.

  According to the sixth aspect of the invention, the base ignition timing is corrected to the retard side as the required ignition timing is retarded according to the operating state, thereby suppressing the change in the ignition timing retard amount from the required ignition timing. can do. For this reason, according to this invention, the change of the torque change amount with respect to the change amount of the ignition timing can be reduced, and the idling stability can be enhanced.

It is a figure for demonstrating the system configuration | structure of Embodiment 1 of this invention. It is a figure for demonstrating the idle speed correction control map used in Embodiment 1 of this invention. It is a figure for demonstrating the ignition retard amount-correction coefficient map used in Embodiment 1 of this invention. It is a flowchart of the control routine which ECU50 performs in Embodiment 1 of this invention. It is a figure for demonstrating the ethanol concentration-correction coefficient map used in Embodiment 2 of this invention. It is a flowchart of the control routine which ECU50 performs in Embodiment 2 of this invention. It is a figure for demonstrating the engine load factor-correction coefficient map used in Embodiment 3 of this invention. It is a flowchart of the control routine which ECU50 performs in Embodiment 3 of this invention. It is a figure for demonstrating the ignition timing guard reference | standard map used in Embodiment 4 of this invention. It is a figure for demonstrating the ethanol concentration-guard correction coefficient map used in Embodiment 4 of this invention. It is a figure for demonstrating the water temperature-guard correction coefficient map used in Embodiment 4 of this invention. It is a flowchart of the main routine which ECU50 performs in Embodiment 4 of this invention. It is a flowchart of the subroutine which ECU50 performs in Embodiment 4 of this invention. It is a relationship figure which shows the relationship between the intake valve late opening timing and required ignition timing (MBT) in the cold valve control of Embodiment 5 of this invention. It is a figure for demonstrating the intake valve slow open timing-correction coefficient map used in Embodiment 5 of this invention. It is a flowchart of the control routine which ECU50 performs in Embodiment 5 of this invention. It is a figure for demonstrating the ethanol concentration-base ignition timing correction amount map used in Embodiment 6 of this invention. It is a flowchart of the control routine which ECU50 performs in Embodiment 6 of this invention. It is a relationship figure which shows the relationship between ignition timing and a torque.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to the element which is common in each figure, and the overlapping description is abbreviate | omitted.

Embodiment 1 FIG.
[System Configuration of Embodiment 1]
First, Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1 is a diagram for explaining a system configuration according to the first embodiment of the present invention. As shown in FIG. 1, the system of the present embodiment includes an internal combustion engine (hereinafter simply referred to as “engine”) 10 used as a power source for a vehicle. An intake passage 12 and an exhaust passage 14 are connected to the engine 10.

  The engine 10 has a plurality of cylinders, and FIG. 1 shows a cross section of one of the cylinders. Each cylinder is provided with an intake port communicating with the intake passage 12 and an exhaust port communicating with the exhaust passage 14. In the intake port, an injector 16 for injecting fuel is disposed. As fuel, in addition to gasoline fuel, a mixed fuel of gasoline and alcohol (for example, ethanol) is used. The engine 10 is not limited to the configuration shown in the figure, and may be a system in which fuel is directly injected into the cylinder.

  Each cylinder has an intake valve 18 that opens and closes between the intake port and the combustion chamber, an exhaust valve 20 that opens and closes between the exhaust port and the combustion chamber, and ignition for igniting an air-fuel mixture in the combustion chamber. A plug 22 and a piston 24 are provided.

  The reciprocating motion of the piston 24 of each cylinder is converted into the rotational motion of the crankshaft 26 via the crank mechanism. A crank angle sensor 28 for detecting the rotation angle of the crankshaft 26 is attached in the vicinity of the crankshaft 26. According to the output of the crank angle sensor 28, the engine speed can also be detected.

  An air flow meter 30 that detects the amount of intake air is disposed in the intake passage 12. A throttle valve 32 is disposed downstream of the air flow meter 30. The throttle valve 32 is an electronically controlled throttle valve that is driven to open and close by a throttle motor 34 in accordance with a command from the ECU 50 described later. In the vicinity of the throttle valve 32, a throttle position sensor 36 for detecting the throttle opening is disposed.

  A catalyst 38 for purifying exhaust gas is installed in the exhaust passage 14. As the catalyst 38, for example, a three-way catalyst, a NOx catalyst, or the like is used.

  The system of this embodiment includes an ECU (Electronic Control Unit) 50. On the input side of the ECU 50, in addition to the crank angle sensor 28, the air flow meter 30, and the throttle position sensor 36, an accelerator position sensor 52 that detects the accelerator pedal position of the vehicle, and a coolant temperature that detects the coolant temperature of the engine 10. Various sensors such as a sensor 54 and an ethanol concentration sensor 56 for detecting the ethanol concentration in the fuel are connected.

  Further, on the output side of the ECU 50, various actuators such as the injector 16, the spark plug 22, and the throttle motor 34 are connected. The ECU 50 controls the operating state of the engine 10 by executing predetermined programs based on input information from various sensors and operating various actuators.

  The ECU 50 performs control to set the reference ignition timing to a timing retarded from MBT (Minimum advance for Best Torque) (hereinafter referred to as base ignition timing) during warm idling (for example, after warm-up). To do. In order to improve emissions, the ECU 50 delays the reference ignition timing during cold idling by a predetermined ignition delay amount further than the base ignition timing during warm idling (hereinafter referred to as retard ignition timing). The ignition timing retarding control that is set in the above) is implemented.

  The ECU 50 also feeds back the fluctuation amount of the engine speed during idling to the ignition timing in addition to the throttle opening and the injection amount so that the fluctuation amount of the engine speed during idling is reduced (closer to 0). The idle speed correction control is performed.

[Characteristic Control in Embodiment 1]
FIG. 19 is a relationship diagram illustrating the relationship between the ignition timing and the torque. The base ignition timing sabase in FIG. 19 represents a reference ignition timing set during warm idling. Further, the ignition retard amount saretard in FIG. 19 represents the retard amount further retarded from the base ignition timing sabase in the large ignition timing retard control during cold idling. As shown in FIG. 19, as the torque characteristic with respect to the ignition timing, the torque change amount with respect to the ignition timing change amount (Δtorque with respect to Δignition timing in FIG. 19) increases as the ignition timing is retarded.

  In the system configuration described above, the ignition timing is retarded greatly during cold idling in order to improve emissions. Therefore, during cold idling, the amount of torque change relative to the change in ignition timing is greater than during warm idling. growing. In this case, if the above-described idle rotation speed correction control is performed and the ignition timing is changed to the advance side or the retard side as in the warm state, the torque may change greatly and overcorrection may occur. As a result, the engine speed fluctuates greatly, and the idling stability may be deteriorated.

  Therefore, in the system of the present embodiment, control is performed that can appropriately correct the ignition timing in the idle speed correction control even when the reference ignition timing of the idle is changed.

(Idle speed correction control map)
A more specific outline of control will be described with reference to FIGS. First, the “idle speed correction control map” used in the idle speed correction control for correcting the ignition timing to the advance side or the retard side in accordance with the fluctuation of the engine speed during idling will be described. FIG. 2 is a diagram for explaining the idle speed correction control map.

  In FIG. 2, when the engine speed increases instantaneously, the instantaneous rotation difference ΔNE increases to the positive value side. As the instantaneous rotation difference ΔNE increases toward the positive value side, the ignition timing correction amount saΔne decreases (increases toward the negative value side). The ignition timing correction amount saΔne is a correction amount for correcting the ignition timing to the retard side when the value is negative. By correcting the ignition timing to the retard side, the torque can be reduced and the engine speed can be lowered.

  In FIG. 2, when the engine speed decreases instantaneously, the instantaneous rotation difference ΔNE increases toward the negative value side (decreases toward the positive value side). When the instantaneous rotation difference ΔNE increases to the negative value side, the ignition timing correction amount saΔne increases to the positive value side. The ignition timing correction amount saΔne is a correction amount for correcting the ignition timing to the advance side at a positive value. By correcting the ignition timing to the advance side, the torque can be increased and the engine speed can be increased.

(Ignition retardation amount-Correction coefficient map)
By the way, as described above, when the ignition timing retarding control is largely performed at the time of cold idling, the reference ignition timing is largely retarded as compared with that at the time of warm idling. The amount of change increases. In FIG. 2, the ignition timing correction amount saΔne is determined according to the instantaneous rotation difference ΔNE. However, if the reference ignition timing is different, the torque change amount with respect to the ignition timing correction amount saΔne also differs. Therefore, the ignition timing correction amount saΔne is appropriately corrected based on an “ignition retardation amount-correction coefficient map” described below. FIG. 3 is a diagram for explaining the ignition retard amount-correction coefficient map.

  FIG. 3 shows the relationship between the ignition retard amount saretard and the correction coefficient kretard. As shown in FIG. 3, the correction coefficient kretard decreases from 1 as the ignition retard amount saretard increases. That is, the correction coefficient kretard decreases as the reference ignition timing (retard ignition timing) is set to the retard side. Therefore, in the system of the present embodiment, by multiplying the ignition timing correction amount saΔne by the correction coefficient kretard, the amount of change in the ignition timing can be reduced as the reference ignition timing is set to the retard side. As a result, the amount of torque change can be appropriately corrected even in the retarded angle region, and the idling stability can be improved.

(Control routine)
FIG. 4 is a flowchart of a control routine executed by the ECU 50 in order to realize the above-described operation. In the routine shown in FIG. 4, first, at step 100, it is determined whether or not an idle condition is satisfied. The ECU 50 determines whether or not a condition is satisfied based on input information from various sensors such as accelerator OFF and throttle closing. If it is determined that the idle condition is not satisfied, then the processing of this routine is terminated (step 110).

  On the other hand, if it is determined that the idle condition is satisfied, then in step 120, the average engine speed NE is acquired. The average engine speed NE is obtained by calculating the average engine speed during idling detected by the crank angle sensor 28.

  Subsequently, in step 130, the immediately preceding engine speed ne is acquired. The immediately preceding engine speed ne is the latest detected value detected by the crank angle sensor 28.

  In step 140, the instantaneous engine speed difference NE is calculated by subtracting the average engine speed NE from the immediately preceding engine speed ne. The instantaneous rotation difference ΔNE takes a positive value when the immediately preceding engine speed ne exceeds the average engine speed NE, and takes a negative value when it falls below the average engine speed NE.

  In step 150, the base ignition timing sabase and the ignition retard amount saretard are acquired. Specifically, the ECU 50 stores in advance an idle base ignition timing sabase and an ignition retard amount saretard. The ignition retard amount saretard is set, for example, to 0 when the coolant of the engine 10 is warm (for example, after warming up), and to a positive value when the coolant is warm. (FIG. 19). The ignition retard amount saretard may be calculated according to the operating state.

  In step 160, an ignition timing correction amount saΔne for the instantaneous rotation difference ΔNE is obtained. Specifically, the ECU 50 stores the idling speed correction control map shown in FIG. 2 described above. From the idle speed correction control map, the ignition timing correction amount saΔne corresponding to the instantaneous speed difference ΔNE is acquired.

  In step 170, a correction coefficient kretard corresponding to the ignition retard amount saretard is obtained. Specifically, the ECU 50 stores the ignition retard amount-correction coefficient map shown in FIG. 3 described above. A correction coefficient kretard corresponding to the ignition retard amount saretard is acquired from the ignition retard amount-correction coefficient map.

In step 180, the final ignition timing SA is calculated from equation (1). The above-described large ignition timing retard control is performed according to the ignition retard amount saretard, and the reference ignition timing is set to the retard side.
Final ignition timing SA = Base ignition timing sabase-Ignition retardation amount saretard
+ (Ignition timing correction amount saΔne x correction coefficient kretard) (1)

  Thereafter, the spark plug 22 is driven according to the final ignition timing SA. Thereafter, the processing of this routine is terminated, and the processing from step 100 is repeatedly executed.

  As described above, according to the routine shown in FIG. 4, the ignition timing correction amount increases as the ignition retard amount saretard increases, that is, as the reference ignition timing (retard ignition timing) is in the retarded region. Correction can be made to reduce saΔne. Since the torque change amount with respect to the ignition timing change amount becomes larger as the retard angle side region is corrected, it is possible to suppress the torque from changing excessively by correcting the ignition timing correction amount saΔne. it can. For this reason, according to the system of the present embodiment, even when the reference retardation amount is greatly changed during idling, the ignition timing correction amount saΔne for performing the idle speed correction control is appropriately corrected, Idle stability can be improved regardless of whether it is cold or warm.

  In the first embodiment described above, the ECU 50 executes the process of step 150, so that the “ignition retarding amount acquisition means” in the first aspect of the invention executes the process of step 140. The “instantaneous fluctuation rotational speed acquisition means” in the first invention realizes the “ignition timing correction amount calculation means” in the first invention by executing the above step 180 processing.

  Furthermore, in the first embodiment, the ignition timing correction amount saΔne obtained in step 160 is the “instantaneous variable rotational speed correction amount” in the first invention, and the correction coefficient kretard obtained in step 170 is the first coefficient. This corresponds to the “ignition retarding amount correction coefficient” in the present invention.

Embodiment 2. FIG.
[System Configuration of Embodiment 2]
Next, a second embodiment of the present invention will be described with reference to FIGS. The system of the present embodiment can be realized by causing the ECU 50 to execute the routine of FIG. 6 described later in the configuration shown in FIG.

[Characteristic Control in Embodiment 2]
FIG. 19 shows the relationship between ignition timing and torque for fuels (E0, E85) having different ethanol concentrations. The higher the ethanol concentration in the fuel, the faster the burning rate. Therefore, as shown in FIG. 19, the torque change amount with respect to the ignition timing change amount decreases as the ethanol concentration increases.

  Therefore, in the system of the present embodiment, control is performed to appropriately correct the ignition timing in the idle rotation speed correction control according to the ethanol concentration.

(Ethanol concentration-correction coefficient map)
An outline of more specific control will be described with reference to FIG. FIG. 5 is a diagram for explaining an ethanol concentration-correction coefficient map used in the system of the second embodiment. FIG. 5 shows the relationship between the ethanol concentration Et in the fuel and the correction coefficient ket. As shown in FIG. 5, the correction coefficient ket is higher than 1 as the ethanol concentration Et is higher. Therefore, in the system of this embodiment, the correction coefficient ket is multiplied by the ignition timing correction amount saΔne described in the first embodiment, so that the higher the ethanol concentration Et, the higher the ignition timing change amount. can do. As a result, the amount of torque change can be appropriately corrected according to the ethanol concentration Et, and the idling stability can be improved.

(Control routine)
FIG. 6 is a flowchart of a control routine executed by the ECU 50 in order to realize the above-described operation. This routine is the same as the routine shown in FIG. 4 except that Step 200 to Step 210 are added after Step 170 and Step 180 is replaced with Step 220. Hereinafter, in FIG. 6, the same steps as those shown in FIG. 4 are denoted by the same reference numerals, and the description thereof is omitted or simplified.

  In the routine shown in FIG. 6, after the processing in step 170, the ethanol concentration Et in the fuel is acquired (step 200). The ethanol concentration Et is a detection value detected by the ethanol concentration sensor 56.

  Subsequently, in step 210, a correction coefficient ket corresponding to the ethanol concentration Et is obtained. Specifically, the ECU 50 stores the ethanol concentration-correction coefficient map shown in FIG. A correction coefficient ket corresponding to the ethanol concentration Et is acquired from the ethanol concentration-correction coefficient map.

In step 220, the final ignition timing SA is calculated from equation (2). Note that, as described in the first embodiment, the significant ignition timing retardation control is performed in accordance with the ignition retardation amount saretard.
Final ignition timing SA = Base ignition timing sabase-Ignition retardation amount saretard
+ (Ignition timing correction amount saΔne × correction coefficient kretard × ket) (2)

  Thereafter, the spark plug 22 is driven according to the final ignition timing SA. Thereafter, the processing of this routine is terminated, and the processing from step 100 is repeatedly executed.

  As described above, according to the routine shown in FIG. 6, the ignition timing correction amount saΔne can be corrected so as to increase as the ethanol concentration Et increases. The higher the ethanol concentration Et, the smaller the torque change amount with respect to the ignition timing change amount. Therefore, the torque change amount can be compensated by correcting the ignition timing correction amount saΔne to be increased. For this reason, according to the system of the present embodiment, the ignition timing correction amount saΔne for performing the idle speed correction control can be appropriately corrected according to the ethanol concentration Et, and the idling stability can be improved.

  By the way, in the system of the second embodiment described above, the correction coefficient kretard is acquired in the processing of step 170 and used for correcting the ignition timing correction amount saΔne in the processing of step 220. The correction is not limited to this. The ignition timing correction amount saΔne may be corrected with the correction coefficient ket without using the correction coefficient kretard.

  In the second embodiment described above, the ethanol concentration sensor 56 corresponds to the “concentration acquisition means” in the second invention. Furthermore, in the second embodiment, the correction coefficient ket obtained in step 210 corresponds to the “ethanol concentration correction coefficient” in the second invention.

Embodiment 3 FIG.
[System Configuration of Embodiment 3]
Next, a third embodiment of the present invention will be described with reference to FIGS. The system of the present embodiment can be realized by causing the ECU 50 to execute a routine of FIG. 8 described later in the configuration shown in FIG.

[Characteristic Control in Embodiment 3]
FIG. 19 shows the relationship between ignition timing and torque for different engine loads. The higher the engine load, the larger the torque change amount with respect to the ignition timing change amount. Therefore, in the system of the present embodiment, control is performed to appropriately correct the ignition timing in the idle speed correction control according to the engine load.

(Engine load factor-correction factor map)
An outline of more specific control will be described with reference to FIG. FIG. 7 is a diagram for explaining an engine load factor-correction coefficient map used in the system according to the third embodiment. FIG. 7 shows the relationship between the engine load factor kl and the correction coefficient kkl. As shown in FIG. 7, the correction coefficient kkl becomes lower than 1 as the engine load factor kl increases. Therefore, in the system of the present embodiment, by multiplying the correction coefficient kkl by the ignition timing correction amount saΔne described in the first embodiment, the amount of change in the ignition timing is reduced as the engine load factor kl increases. It can be corrected. As a result, the amount of change in torque can be corrected appropriately according to the engine load factor kl, and the idling stability can be improved.

(Control routine)
FIG. 8 is a flowchart of a control routine executed by the ECU 50 in order to realize the above-described operation. This routine is the same as the routine shown in FIG. 6 except that step 300 to step 310 are added after the process of step 210, and the process of step 220 is replaced with step 320. In FIG. 8, the same steps as those shown in FIG. 6 are denoted by the same reference numerals, and the description thereof is omitted or simplified.

  In the routine shown in FIG. 8, after the process of step 210, the engine load factor kl is acquired (step 300). The engine load factor kl is a value calculated from the engine speed detected by the crank angle sensor 28, the intake air amount detected by the air flow meter 30, the fuel injection amount injected by the injector 16, and the like.

  Subsequently, in step 310, a correction coefficient kkl corresponding to the engine load factor kl is obtained. Specifically, the ECU 50 stores the engine load factor-correction coefficient map shown in FIG. A correction coefficient kkl corresponding to the engine load factor kl is acquired from the engine load factor-correction coefficient map.

In step 320, the final ignition timing SA is calculated from equation (3). Note that, as described in the first embodiment, the significant ignition timing retardation control is performed in accordance with the ignition retardation amount saretard.
Final ignition timing SA = Base ignition timing sabase-Ignition retardation amount saretard
+ (Ignition timing correction amount saΔne × correction coefficient kretard × ket × kkl) (3)

  Thereafter, the spark plug 22 is driven according to the final ignition timing SA. Thereafter, the processing of this routine is terminated, and the processing from step 100 is repeatedly executed.

  As described above, according to the routine shown in FIG. 8, the ignition timing correction amount saΔne can be corrected to decrease as the engine load factor kl increases. Since the torque change amount with respect to the ignition timing change amount increases as the engine load factor kl increases, the torque change can be suppressed by correcting the ignition timing correction amount saΔne to be decreased. Therefore, according to the system of the present embodiment, it is possible to appropriately correct the ignition timing correction amount saΔne for performing the idle speed correction control according to the engine load factor kl, and to improve the idle stability. .

  By the way, in the system of the third embodiment described above, the correction coefficient kretard is acquired in the process of step 170, the correction coefficient ket is acquired in the process of step 210, and these are calculated for the ignition timing correction amount saΔne in the process of step 320. Although used for correction, the correction method of the ignition timing correction amount saΔne is not limited to this. It is only necessary to correct the ignition timing correction amount saΔne by the correction coefficient kkl.

  In the third embodiment described above, the “load factor acquisition means” according to the third aspect of the present invention is implemented when the ECU 50 executes the processing of step 300. Furthermore, in the third embodiment, the correction coefficient kkl obtained in step 310 corresponds to the “engine load factor correction coefficient” in the third aspect of the invention.

Embodiment 4 FIG.
[System Configuration of Embodiment 4]
Next, a fourth embodiment of the present invention will be described with reference to FIGS. The system of the present embodiment can be realized by causing the ECU 50 to execute the routines of FIGS. 12 and 13 described later in the configuration shown in FIG.

[Characteristic Control in Embodiment 4]
In the system described in the third embodiment, the required ignition timing increases toward the advance side as the ethanol concentration in the fuel and the engine load increase. Therefore, in the system of the present embodiment, control is performed to appropriately guard the maximum advance amount of the ignition timing in the idle speed correction control according to the ethanol concentration and the engine load.

(Ignition timing guard reference map)
A more specific outline of the control will be described with reference to FIGS. First, the “ignition timing guard reference map” used for obtaining the guard reference value of the maximum advance amount of the ignition timing will be described. FIG. 9 is a diagram for explaining the ignition timing guard reference map.

  FIG. 9 shows the base ignition timing guard saguardb corresponding to the engine speed NE and the engine load factor kl. The base ignition timing guard saguardb is a guard reference value for the maximum advance amount of the ignition timing, and is a value indicating the advance amount before the top dead center (BTDC). As shown in FIG. 9, in the region where the engine speed NE is high and the engine load factor kl is low, a large advance amount before the top dead center is set in the base ignition timing guard saguardb. On the other hand, in the region where the engine speed NE is low and the engine load factor kl is high, the base ignition timing guard saguardb is set to a small advance amount before top dead center.

(Ethanol concentration-guard correction coefficient map)
As described above, the required ignition timing increases toward the advance side as the ethanol concentration in the fuel increases. Therefore, the base ignition timing guard saguardb is appropriately corrected based on the “ethanol concentration-guard correction coefficient map” described below. FIG. 10 is a diagram for explaining the ethanol concentration-guard correction coefficient map.

  FIG. 10 shows the relationship between the ethanol concentration Et in the fuel and the guard correction coefficient kget. As shown in FIG. 10, the guard correction coefficient kget becomes lower than 1 as the ethanol concentration Et increases. Therefore, in the system of the present embodiment, the guard correction coefficient kget is multiplied by the base ignition timing guard saguardb in FIG. 9, so that the higher the ethanol concentration Et, the more the guard value for the maximum advance amount of the ignition timing is delayed. It can be corrected.

(Water temperature-guard correction coefficient map)
FIG. 11 is a diagram for explaining a water temperature-guard correction coefficient map. FIG. 11 shows the relationship between the cooling water temperature (water temperature thw) and the guard correction coefficient kgthw. As shown in FIG. 11, the guard correction coefficient kgthw becomes higher than 1 as the water temperature thw is lower. Therefore, in the system of the present embodiment, the maximum ignition timing is obtained when the temperature of the coolant of the engine 10 is low (during cold) by multiplying the base correction timing guard saguardb of FIG. 9 by the guard correction coefficient kgthw. The advance amount guard value can be corrected to the advance side.

(Control routine)
FIG. 12 is a flowchart of a main routine executed by the ECU 50 in order to realize the above-described operation. This routine is the same as the routine shown in FIG. 8 except that steps 400 to 420 are added after the processing of step 320. In FIG. 12, the same steps as those shown in FIG. 8 are denoted by the same reference numerals, and the description thereof is omitted or simplified.

  In the routine shown in FIG. 12, after the process of step 320, the final guard saguard of the required ignition timing according to the ethanol concentration Et, the engine load factor kl, and the water temperature thw is obtained (step 400). Specific processing in step 400 will be described with reference to FIG. FIG. 13 is a flowchart of a subroutine executed by the ECU 50 in step 400.

  In the subroutine shown in FIG. 13, first, at step 412, the base ignition timing guard saguardb is obtained from the engine speed NE and the engine load factor kl. Specifically, the ECU 50 stores the ignition timing guard reference map shown in FIG. 9 described above. The base ignition timing guard saguardb corresponding to the engine speed NE and the engine load factor kl is acquired from the ignition timing guard reference map.

  Subsequently, in step 414, a guard correction coefficient kget corresponding to the ethanol concentration Et and a guard correction coefficient kgthw corresponding to the water temperature thw are obtained. The ECU 50 stores the ethanol concentration-guard correction coefficient map shown in FIG. 10 and the water temperature-guard correction coefficient map shown in FIG. A guard correction coefficient kget corresponding to the ethanol concentration Et is obtained from the ethanol concentration-guard correction coefficient map. A guard correction coefficient kgthw corresponding to the water temperature thw is acquired from the water temperature-guard correction coefficient map.

In step 416, the final guard saguard is calculated from equation (4).
Final guard saguard = Base ignition timing guard saguardb × correction factor kget × kgthw
... (4)

  Thereafter, returning to the control routine of FIG. 12, in step 410, it is determined whether or not the final ignition timing SA obtained in step 320 is smaller than the final guard saguard. When the final ignition timing SA is smaller, it can be determined that the ignition timing has not advanced to the guard value. On the other hand, when the final ignition timing SA is equal to or greater than the final guard saguard, it can be determined that the advance is beyond the guard. In this case, in step 420, the final ignition timing SA is changed to the final guard saguard.

  Thereafter, the spark plug 22 is driven according to the final ignition timing SA. Thereafter, the processing of this routine is terminated, and the processing from step 100 is repeatedly executed.

  As described above, according to the routines shown in FIG. 12 and FIG. 13, the higher the ethanol concentration Et and the engine load factor kl, the higher the advance amount before the top dead center can be guarded to the delay side. For this reason, according to the system of this embodiment, knocking can be suppressed and idle stability can be enhanced.

  By the way, in the system of the fourth embodiment described above, the correction coefficient kretard is acquired in the process of step 170, the correction coefficient ket is acquired in the process of step 210, the correction coefficient kkl is acquired in the process of step 310, and these Is used for correcting the ignition timing correction amount saΔne in the process of step 320, but the correction of the ignition timing correction amount saΔne is not limited to this. The ignition timing correction amount saΔne may be corrected with some correction coefficients, or correction may not be performed.

  In the fourth embodiment described above, the ethanol concentration sensor 56 corresponds to the “concentration acquisition means” in the fourth invention. In the fourth embodiment described above, the ECU 50 executes the process of step 300, so that the “load factor acquisition means” in the fourth aspect of the invention executes the processes of step 400 to step 416. Thus, the “guard setting means” according to the fourth aspect of the invention realizes the “ignition timing changing means” according to the fourth aspect of the invention by executing the processing of steps 410 to 420 described above. Furthermore, in the fourth embodiment, the final guard saguard obtained in the above step 416 corresponds to the “upper limit advance amount” in the fourth aspect of the invention.

Embodiment 5 FIG.
[System Configuration of Embodiment 5]
Next, a fifth embodiment of the present invention will be described with reference to FIGS. The system of the present embodiment can be realized by causing the ECU 50 to execute a routine of FIG. 16 described later in a configuration in which a variable valve mechanism described later is added to the configuration shown in FIG.

  The engine 10 includes a variable valve mechanism (not shown) that variably sets the operating angle and lift amount of the intake valve 18. The variable valve mechanism has a known configuration as described in, for example, Japanese Patent Application Laid-Open No. 2001-263015, and changes the opening / closing characteristics of the valve in accordance with a control signal input from the ECU 50.

  When the variable valve mechanism is operated, the operating angle of the intake valve 18 and the lift amount are changed together. That is, when the operating angle of the intake valve 18 is sequentially changed from the small operating angle to the medium operating angle and the large operating angle by the variable valve mechanism, the lift amount of the valve also changes from the small lift amount to the medium lift amount and the large lift amount. And change sequentially.

  Further, the engine 10 includes a VVT (Variable Valve Timing system) (not shown) as a phase angle variable mechanism that variably sets the phase angle of the intake valve 18. VVT has a known configuration as disclosed in, for example, Japanese Patent Laid-Open No. 2000-87769. The VVT can advance and retard the phase angle of the intake valve 18 in accordance with a control signal input from the ECU 50.

  The variable valve mechanism and the actuator for controlling the VVT are connected to the output side of the ECU 50. Further, the ECU 50 constitutes intake valve slow opening control means, and executes cold valve control described below.

(Cold valve control)
In the system configuration of this embodiment described above, the ECU 50 controls the variable valve mechanism, VVT, etc., reduces the lift amount of the intake valve 18 during cold operation, and sets the opening timing of the intake valve 18 to the intake stroke. By setting the timing later than the top dead center, the flow velocity of the intake air flowing into the combustion chamber is increased. By increasing the flow rate of the intake air, the turbulence of the air flow in the combustion chamber increases and the combustion speed increases. On the other hand, by reducing the lift amount, there is an effect that the flow of the entire intake air in the intake stroke is attenuated. The turbulence intensity in the vicinity of TDC in the compression stroke is determined by combining both turbulences.

[Characteristic Control in Embodiment 5]
FIG. 14 is a relationship diagram showing the relationship between the intake valve delay timing and the required ignition timing (MBT) in the cold valve control. In the system of this embodiment, the state of large cam (large lift), large working angle, small ATDC (After Top Dead Center), and state of small cam (small lift), small working angle, large ATDC And are continuously changed. As shown in FIG. 14, the required ignition timing (MBT) is greatly retarded at the large lift large operating angle and the small lift small operating angle, and is greatly advanced toward the vicinity of the intermediate lift operating angle. Therefore, in the system of the present embodiment, control is performed to appropriately correct the ignition timing by the idle speed correction control in accordance with the intake valve delay opening timing.

(Intake valve late opening timing-correction coefficient map)
FIG. 15 is a diagram for explaining an intake valve delay timing-correction coefficient map used in the system of the fifth embodiment. FIG. 15 shows the relationship between the intake valve delay timing and the correction coefficient kinadc. In the region where the MBT shown in FIG. 14 is retarded, the correction coefficient kinadc shown in FIG. 15 is set large. By multiplying the large correction coefficient kinadc by the ignition timing correction amount saΔne described in the first embodiment, correction can be made to increase the amount of change in the ignition timing. On the other hand, in the region where the MBT shown in FIG. 14 is advanced, the correction coefficient kinadc shown in FIG. 15 is set small (close to 1). By multiplying the ignition timing correction amount saΔne by a small correction coefficient kinadc, correction for the change amount of the ignition timing can be suppressed.

(Control routine)
FIG. 16 is a flowchart of a control routine executed by the ECU 50 in order to realize the above-described operation. This routine is the same as the routine shown in FIG. 4 except that Step 500 to Step 510 are added after Step 170, and Step 180 is replaced with Step 520. In FIG. 16, the same steps as those shown in FIG. 4 are denoted by the same reference numerals, and the description thereof is omitted or simplified.

  In the routine shown in FIG. 16, after the process of step 170, the intake valve delay timing Inatdc is acquired (step 500). The intake valve delay timing Inatdc is determined according to the control values for the variable valve mechanism, VVT, and the like in the cold valve control described above.

  Subsequently, in step 510, a correction coefficient kinatdc corresponding to the intake valve delay opening timing Inatdc is obtained. Specifically, the ECU 50 stores the intake valve delay opening timing-correction coefficient map shown in FIG. From the intake valve delay opening timing-correction coefficient map, the correction coefficient kinadc corresponding to the intake valve delay opening timing Inatdc is acquired.

In step 220, the final ignition timing SA is calculated from equation (5). As described in the first embodiment, the significant ignition timing retard control is performed in accordance with the ignition retard amount saretard.
Final ignition timing SA = Base ignition timing sabase-Ignition retardation amount saretard
+ (Ignition timing correction amount saΔne × correction coefficient kretard × kinatdc) (5)

  Thereafter, the spark plug 22 is driven according to the final ignition timing SA. Thereafter, the processing of this routine is terminated, and the processing from step 100 is repeatedly executed.

  As described above, according to the routine shown in FIG. 16, when the cold valve control is performed, the ignition timing correction amount saΔne for performing the idle speed correction control according to the intake valve delay opening timing Inatdc. Can be corrected appropriately, and the idling stability can be improved.

  By the way, in the system of the fifth embodiment described above, the correction coefficient kretard is acquired in the process of step 170 and used for correcting the ignition timing correction amount saΔne in the process of step 520. The correction is not limited to this. The correction coefficient ket in the process of step 210 and the correction coefficient kkl in the process of step 310 may be used for correcting the ignition timing correction amount saΔne.

  In the system of the fifth embodiment described above, the processes of steps 400 to 420 described above may be added after the process of step 520.

  In the fifth embodiment described above, the variable valve mechanism is the “variable valve mechanism” in the fifth aspect of the invention, and the cold valve control is the “intake valve slow opening control means” in the fifth aspect of the invention. , Respectively. Furthermore, in the fifth embodiment, the correction coefficient kinatdc obtained in step 510 corresponds to the “intake valve delay opening correction coefficient” in the fifth aspect of the invention.

Embodiment 6 FIG.
[System Configuration of Embodiment 6]
Next, a sixth embodiment of the present invention will be described with reference to FIGS. The system of the present embodiment can be realized by causing the ECU 50 to execute a routine of FIG. 18 to be described later in the configuration shown in FIG.

[Characteristic Control in Embodiment 6]
In the above-described second to fifth embodiments, it is possible to suitably correct the deviation of the torque change amount with respect to the change amount of the ignition timing caused by the deviation of the required ignition timing (MBT) due to the respective factors (FIG. 19). On the other hand, in the system according to the present embodiment, the ignition timing retard amount from MBT is maintained constant by correcting the base ignition timing sabase with respect to the deviation of the required ignition timing (MBT), and the ignition timing It is characterized by reducing the deviation of the torque fluctuation amount with respect to the fluctuation amount (FIG. 19).

(Ethanol concentration-base ignition timing correction amount map)
A more specific outline of control will be described with reference to FIG. FIG. 17 is a diagram for explaining an ethanol concentration-base ignition timing correction amount map used in the system of the sixth embodiment. FIG. 17 shows the relationship between the ethanol concentration Et in the fuel and the base ignition timing correction amount kbet. As shown in FIG. 17, the base ignition timing correction amount kbet increases as the ethanol concentration Et increases. Therefore, in the system of the present embodiment, the base ignition timing sabase is corrected to the retard side as the ethanol concentration Et is higher by subtracting the base ignition timing correction amount kbet from the base ignition timing sabase described in the first embodiment. To do. By absorbing the deviation of the MBT due to the ethanol concentration by correcting the base ignition timing, the ignition timing retardation amount from the MBT can be made constant. As a result, the deviation of the torque change amount with respect to the change amount of the ignition timing is reduced, an appropriate torque can be obtained, and the idling stability can be enhanced.

(Control routine)
FIG. 18 is a flowchart of a control routine executed by the ECU 50 in order to realize the above-described operation. This routine is the same as the routine shown in FIG. 4 except that Steps 600 to 610 are added between Step 150 and Step 160, and the processing of Step 180 is replaced with Step 620. In FIG. 18, the same steps as those shown in FIG. 4 are denoted by the same reference numerals, and the description thereof is omitted or simplified.

  In the routine shown in FIG. 18, after the process of step 150, the ethanol concentration Et in the fuel is acquired (step 600). The ethanol concentration Et is a detection value detected by the ethanol concentration sensor 56.

  Subsequently, in step 610, a base ignition timing correction amount kbet corresponding to the ethanol concentration Et is obtained. Specifically, the ECU 50 stores the ethanol concentration-base ignition timing correction amount map shown in FIG. 17 described above. A base ignition timing correction amount kbet corresponding to the ethanol concentration Et is acquired from the ethanol concentration-base ignition timing correction amount map.

After step 170, in step 620, the final ignition timing SA is calculated from equation (6). As described in the first embodiment, the significant ignition timing retard control is performed in accordance with the ignition retard amount saretard.
Final ignition timing SA = (base ignition timing sabase-base ignition timing correction amount kbet)
-Ignition retard amount saretard + (ignition timing correction amount saΔne x correction coefficient kretard) (6)

  Thereafter, the spark plug 22 is driven according to the final ignition timing SA. Thereafter, the processing of this routine is terminated, and the processing from step 100 is repeatedly executed.

  As described above, according to the routine shown in FIG. 18, the amount of change in the ignition timing is obtained by appropriately correcting the base ignition timing sabase according to the ethanol concentration Et and making the ignition timing retard amount from the MBT constant. This reduces the occurrence of a shift in the amount of torque change with respect to. For this reason, according to the system of this embodiment, the stability of idle can be improved.

  In the system of the sixth embodiment described above, the correction coefficient kretard is acquired in the process of step 170 and used for correcting the ignition timing correction amount saΔne in the process of step 620. The correction is not limited to this. The correction coefficient ket in the process of step 210 and the correction coefficient kkl in the process of step 310 may be used for correcting the ignition timing correction amount saΔne.

  Moreover, in the system of Embodiment 6 mentioned above, it is good also as adding the process of step 400-420 mentioned above after the process of step 620. FIG.

  In the sixth embodiment described above, the “base ignition timing correcting means” according to the sixth aspect of the present invention is realized by the ECU 50 executing the processing of step 600 to step 620 described above.

10 Engine 12 Intake passage 16 Injector 18 Intake valve 22 Spark plug 28 Crank angle sensor 30 Air flow meter 32 Throttle valve 34 Throttle motor 36 Throttle position sensor 50 ECU
52 Accelerator position sensor 54 Cooling water temperature sensor 56 Ethanol concentration sensor
Et ethanol concentration
Inatdc intake valve slow opening timing
kbet Base ignition timing correction amount
ket Correction factor according to ethanol concentration
kget Correction factor according to ethanol concentration guard
kgthw Correction factor according to the water temperature guard
kinatdc Correction coefficient according to intake valve delay timing
kkl Correction factor according to engine load factor
kl engine load factor
kretard Correction coefficient according to ignition delay
ne Last engine speed
NE average engine speed
SA final ignition timing
sabase base ignition timing
saguard final guard
saguardb base ignition timing guard
saretard ignition retard amount
saΔne Ignition timing correction amount
thw Water temperature ΔNE Instantaneous rotation difference

Claims (6)

Ignition retard amount acquisition means for acquiring an ignition delay amount from the base ignition timing of the idle;
Instantaneous fluctuation speed acquisition means for acquiring the instantaneous fluctuation speed of the engine speed during idling;
The larger the instantaneous fluctuation rotational speed is on the plus side, the larger the retarding speed side is. The larger the instantaneous fluctuation rotational speed is on the negative side, the larger the instantaneous fluctuation rotational speed is. Ignition timing correction amount calculating means for calculating a correction amount of the ignition timing for reducing the instantaneous variable rotational speed using an ignition delay amount correction coefficient that decreases the instantaneous variable rotational speed correction amount. An ignition timing control device for an internal combustion engine. A concentration acquisition means for acquiring the ethanol concentration in the fuel;
The ignition timing correction amount calculation means uses the instantaneous variation rotational speed correction amount, the ignition delay amount correction coefficient, and an ethanol concentration correction coefficient that increases the instantaneous variable rotational speed correction amount as the ethanol concentration increases. Calculating the correction amount of the ignition timing,
The ignition timing control device for an internal combustion engine according to claim 1. A load factor acquisition means for acquiring an engine load factor;
The ignition timing correction amount calculating means includes the instantaneous variation rotational speed correction amount, the ignition delay amount correction coefficient, and an engine load factor correction coefficient that decreases the instantaneous variable rotational speed correction amount as the engine load factor increases. To calculate the ignition timing correction amount,
The ignition timing control device for an internal combustion engine according to claim 1 or 2, characterized by the above-mentioned. A concentration acquisition means for acquiring the ethanol concentration in the fuel;
A load factor acquisition means for acquiring an engine load factor;
Guard setting means for setting the upper limit advance amount before the top dead center of the ignition timing to the delay side as the engine load factor and ethanol concentration are higher,
An ignition timing changing means for changing the final ignition timing to the upper limit advance amount when the ignition timing corrected using the correction amount is larger than the upper limit advance amount;
The ignition timing control device for an internal combustion engine according to any one of claims 1 to 3, further comprising: The internal combustion engine
A mechanism for variably setting a working angle and a lift amount of the intake valve, and a variable valve mechanism that reduces the lift amount as the working angle is decreased;
An intake valve delay opening control means for driving the variable valve mechanism to change the opening timing of the intake valve to a timing delayed from the top dead center of the intake stroke;
The ignition timing correction amount calculation means is configured to correct the instantaneous fluctuation rotational speed correction amount according to the instantaneous fluctuation rotational speed correction amount, the ignition delay amount correction coefficient, and the valve opening timing changed by the intake valve delay opening control means. Calculating an ignition timing correction amount using an intake valve delay opening correction coefficient that corrects the amount;
The ignition timing control device for an internal combustion engine according to any one of claims 1 to 4, wherein: Base ignition timing correction means for correcting the base ignition timing to the retard side as the required ignition timing according to the operating state is retarded;
The ignition timing control device for an internal combustion engine according to any one of claims 1 to 5, further comprising:

Images