JP4147932B2 - Engine ignition timing control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ignition timing control device for a spark ignition engine.
[0002]
[Prior art]
As an ignition timing control device for a spark ignition type engine, a device as shown in Patent Document 1 is known. Ignition timing control is generally controlled using the engine speed and cooling water temperature as parameters. In the prior art, the basic ignition timing determined based on the water temperature is taken into account after the initial explosion in consideration of changes in the in-cylinder temperature after starting. Correction processing is performed so that the advance amount decreases as the elapsed time increases. This corresponds to the inconvenience that the coolant temperature does not immediately follow the in-cylinder temperature change because the optimum ignition timing changes as the in-cylinder temperature rises, so that the deviation from the optimum ignition timing occurs.
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-82302
[Problems to be solved by the invention]
However, since the conventional technique corrects the basic advance value determined using the coolant temperature at the start of the start according to the elapsed time from the first explosion, there is a problem that the ignition timing is not always appropriate at the time of restart. . In other words, if the engine is restarted with only the in-cylinder temperature rising without a significant increase in the coolant temperature, such as when stalling immediately after the start-up explosion or when restarting after engine stop operation, the initial advance amount is Since it is set at a low water temperature, it becomes an excessive advance angle with respect to the temperature in the cylinder.
[0005]
SUMMARY OF THE INVENTION
In the present invention, the ignition timing at the start is calculated based on the engine coolant temperature. At this time, at the time of hot restart in which the in-cylinder temperature at the start is larger than the coolant temperature, the ignition timing at the start is corrected to be retarded. As a result, it is possible to avoid an excessive advance angle of the ignition timing when the change in the coolant temperature is small even though the in-cylinder temperature is rising, and to set an appropriate ignition timing.
[0006]
Hot restart can also be determined by directly detecting the coolant temperature and in-cylinder temperature, but the coolant temperature at the time of start is higher than the coolant temperature at the time of stoppage before start and the number of combustions after start in the previous operation Can be determined on the condition that is equal to or greater than a predetermined reference value.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. This embodiment is based on a sequential fuel injection type multi-cylinder engine in which cylinder determination is performed at the time of start cranking, and fuel is injected and supplied in synchronization with the intake stroke or the exhaust stroke of the determined cylinder or cylinder group.
[0008]
FIG. 1 shows a schematic configuration of a four-stroke gasoline engine according to this embodiment. In the figure, an air flow meter 4 and a throttle valve 5 for detecting the intake air amount are provided in the intake pipe 3 of the engine 2, and a fuel injection valve 8 is provided in the intake port 7 near the cylinder 6. The fuel injection valve 8 is provided for each cylinder. The fuel injection valve 8 is configured to be supplied with fuel at a constant pressure by a fuel supply system (not shown) and to inject an amount of fuel corresponding to the valve opening time. The fuel injection amount calculated by the controller 1 is calculated as an injection pulse width corresponding to the valve opening time of the fuel injection valve 8.
[0009]
A crank angle sensor 9 detects the rotation angle of the crankshaft 10 and the engine speed, and outputs a pulsed POS signal and a REF signal. The POS signal is output at a cycle of, for example, 1 degree for each unit rotation angle of the crankshaft 10, and the REF signal is output at a preset reference position of the crankshaft 10. A cam position sensor 11 detects the rotational position of the camshaft 12 and outputs a pulsed PAHSE signal when the camshaft 12 reaches a preset rotational position. Reference numeral 13 denotes an ignition switch. When the starter contact is turned on, the controller 1 supplies an ignition signal to the ignition coil 14 at a predetermined timing and drives a starter motor (not shown). 15 is a water temperature sensor that detects the cooling water temperature as a representative value of the engine temperature, and 16 is an oxygen sensor that detects the oxygen concentration in the exhaust gas.
[0010]
The controller 1 is composed of a microcomputer and its peripheral devices. As an operation state signal, an intake air amount signal from the air flow meter 4, a rotation speed signal from the crank angle sensor 9, a water temperature signal from the water temperature sensor 15, and an oxygen sensor 16 The oxygen concentration signal is input, and the fuel injection amount and the ignition control amount are calculated based on these signals.
[0011]
FIG. 2 is a block diagram showing functions of the controller 1 relating to fuel injection control and ignition control. The cranking determination unit a determines the start of cranking based on the starter signal and the ignition signal from the ignition switch 13. In the cylinder determination unit b, a cylinder determination as to which stroke a certain cylinder of the engine 2 is in is performed based on the PHASE signal from the cam position sensor 11 and the POS signal from the crank angle sensor 9. The engine speed generator c calculates the engine speed from the generation period of the POS signal or REF signal. In the injection pulse width calculation unit d, the basic injection pulse width is determined by a table search or the like based on the intake air amount and the rotational speed, and this is corrected by a water temperature signal or an oxygen concentration signal, and is operated at an intended air-fuel ratio. The injection amount command value is determined as follows. The drive signal output unit e outputs a drive signal for the fuel injection valve 8 based on the injection amount command value. The injection start timing calculation unit f calculates the injection start timing from the injection pulse width and the engine speed when performing injection with the injection end timing management, and determines the drive timing of the fuel injection valve 8 by the drive signal output unit e. to manage. The ignition signal calculation unit g calculates the ignition timing and the energization angle using the rotation speed based on the POS signal or the REF signal from the rotation speed generation unit c, and the ignition signal output unit h refers to the REF signal and the POS signal. However, a primary current is output to the ignition coil in accordance with the calculated ignition timing and energization angle.
[0012]
Next, based on the flowchart shown in FIG. 3 and the subsequent drawings, fuel injection control at the time of start-up under the above configuration will be described. 3 and 4 show a processing routine of start control periodically executed by the controller 1, and FIG. 5 is a timing chart showing the state of ignition timing and the like by the start control over time. Reference symbol S in the flowchart represents a processing step.
[0013]
In FIG. 3, first, in step 1, the state of the ignition switch is examined. When the ignition switch is OFF or turned from ON to OFF, the correction coefficient KCRADV of the starting ignition timing is initialized to 1, and the current process is terminated. When the ignition switch is ON, the process proceeds to the start timing setting process after step 2. In step 2, the basic ignition timing at the time of starting and the determination of whether or not the hot restart condition is satisfied are executed by the processing shown in FIG.
[0014]
In FIG. 4, at step 1, the cooling water temperature TWINT at the start is read, and the basic ignition timing corresponding to the cooling water temperature is set by table search. The table gives general ignition timing characteristics to the cooling water temperature, and is set so that the ignition timing is advanced as the water temperature is lower. Next, in step 2, it is determined whether or not it is a hot restart. The hot restart referred to here is when restarting in a state in which the in-cylinder temperature is rising due to a certain degree of combustion history, although the cooling water temperature has hardly increased compared to the cold start. In this determination, the cooling water temperature TWNKO when the previous operation was stopped due to a stall or engine stop operation, etc. is compared with the TWINT at the start of this time, and when the TWINT is lower than TWNKO or the number of combustions during the previous operation is the reference When it is less than the value, non-hot restart is determined (step 3), and when TWNKO ≧ TWINT and the previous combustion count is equal to or greater than the reference value, it is determined that hot restart is performed (step 4). The number of combustions is calculated from the number of ignition signals after the complete explosion and the engine speed, and stored in the controller. As the determination reference value of the number of combustions, for example, the number of combustions that causes a change in the in-cylinder temperature that requires correction of the ignition timing is checked in advance according to the engine and the result is stored in the controller.
[0015]
In FIG. 3, when the non-hot restart is performed according to the determination result, first, the number of combustions REFCNTS after the start is compared with the reference value KCRADV1 # in step 6, and when REFCNTS ≧ KCRADV1 #, 100 ms is thereafter obtained. Each time the correction coefficient KCRADV is subtracted from the predetermined minute change amount DKCRADV #, the value is newly updated as KCRADV, and then the process proceeds to a process of setting the start timing TADVM in step 4. The decrease correction of the KRADV is executed with a predetermined retardation correction value KCRADVIN # (where 1> KCRADVIN # ≧ 0) as a lower limit value. If REFCNTS <KCRADV1 # in step 6, the process proceeds to step 4 without correcting KCRADV.
[0016]
If it is determined in step 2 that the hot restart has occurred, then in step 3, the retardation correction value KCRADVIN # is substituted for the correction coefficient KCRADV, and then the process proceeds to step 4.
[0017]
In step 4, the starting basic ignition timing read from the water temperature table is subjected to rotation speed correction and correction using the coefficient KCRADV to calculate the starting ignition timing TADVM. As described above, the water temperature table gives the basic ignition timing with the characteristic that the lower the water temperature is, the more advanced it is. The rotation speed correction is also a general correction, and the basic ignition timing is corrected in the advance direction as the rotation speed increases.
[0018]
The correction coefficient KCRADV remains initially 1 at non-hot restart, and the engine is started with the normal ignition timing setting with the basic ignition timing corrected by the rotation speed. However, when the number of combustion exceeds REFCNTS, KCRADV gradually decreases. Therefore, the ignition timing is corrected in the retard direction in accordance with the rise in the in-cylinder temperature. As a result, an appropriate ignition timing is set corresponding to the temperature rise in the cylinder after the start at the cold start. On the other hand, at the time of hot restart, the ignition timing is corrected in the retarded direction from the beginning of the start by KCRADVIN #. Thus, an appropriate ignition timing can be obtained even when the in-cylinder temperature is high from the start. In this way, it is possible to operate at the maximum torque regardless of the in-cylinder temperature state. At the time of hot start, that is, when the engine is warmed up and the cooling water temperature is sufficiently increased, it is not necessary to perform the correction at the time of the hot restart as described above, and the cooling water temperature-basic ignition timing table. Thus, the ignition timing corresponding to the in-cylinder temperature state is obtained from the beginning of the start.
[0019]
FIG. 5 shows a timing chart of this control. The ignition timing characteristics indicated by the solid line in the figure indicate the non-hot restart determination time, and in response to the rise in the combustion chamber temperature after the start and the required ignition timing being retarded, an alternative parameter for the in-cylinder temperature As a result, the number of combustions is counted, and if it exceeds a predetermined value, the ignition timing correction coefficient KCRADV is gradually decreased to delay the ignition timing. The broken line indicates the characteristics at the time of hot restart determination, and the ignition timing is a set value that is retarded in advance from the basic ignition timing by KCRADVIN #. In the figure, symbols IGN and StartSW are an ignition switch and a starter switch, respectively, where 1 indicates an ON state and 0 indicates an OFF state.
[0020]
As in the case of the engine premised on the present embodiment, in order to reduce emissions, when sequential injection is performed from the start and the amount of supplied fuel is made appropriate, the ignition timing is also set appropriately as described above. The effect can be maximized. In other words, the richer the air-fuel ratio, the more retarded the required ignition timing, so it is necessary if the air-fuel ratio can be made lean for the same torque by advancing in reverse, that is, if ignition can be performed with MBT This is because the torque required for starting can be obtained with a minimum amount of fuel.
[0021]
In the above embodiment, the hot restart determination is made from the cooling water temperature change and the combustion history. However, when the engine control unit is energized even during the engine stall, the combustion chamber temperature is estimated by the soak time timer. By doing so, it is also possible to determine hot restart.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an engine according to an embodiment of the present invention.
FIG. 2 is a block diagram illustrating functions of a controller according to the embodiment.
FIG. 3 is a first flowchart of start timing fire timing control executed by the controller.
FIG. 4 is a second flowchart of start timing fire timing control executed by the controller.
FIG. 5 is a timing chart during normal water temperature control in the start-up control.
[Explanation of symbols]
1 controller 2 engine 3 intake pipe 4 air flow meter 5 throttle valve 6 cylinder 7 intake port 8 fuel injection valve 9 crank angle sensor 10 crankshaft 11 cam position sensor 12 camshaft 13 ignition switch 14 ignition coil 15 water temperature sensor 16 oxygen sensor

Claims (9)

In a spark ignition engine having an ignition timing calculating means for calculating an ignition timing at the start based on the engine coolant temperature,
The ignition timing calculation means is configured such that when the cooling water temperature at the time of starting is higher than the cooling water temperature at the time of operation stop before starting and the number of combustions after starting in the previous operation is equal to or greater than a predetermined reference value , cylinder temperature is compared to the cooling water temperature is judged that hot restart is larger, it is configured to correct the ignition timing is retarded at the time of the starting,
An ignition timing control device for an engine.   2. The engine ignition timing control device according to claim 1, wherein the ignition timing calculation means corrects the retardation of the ignition timing calculated based on the engine speed and the coolant temperature at the time of hot restart. In a spark ignition engine having an ignition timing calculating means for calculating an ignition timing at the start based on the engine coolant temperature,
The ignition timing calculation means is configured such that when the cooling water temperature at the time of starting is higher than the cooling water temperature at the time of operation stop before starting and the number of combustions after starting in the previous operation is equal to or greater than a predetermined reference value, with cylinder temperature is determined to hot restart is larger compared to the cooling water temperature, is set correction calculation equation having a coefficient KCRADV for correcting the ignition timing at the time of startup, the KCRADV is the time Ho Tsu tri start non-hot Set to correct the ignition timing at the start in the retarded direction rather than at the restart,
An ignition timing control device for an engine.   4. The engine ignition timing control device according to claim 3, wherein the ignition timing calculation means corrects the retard by applying a correction coefficient KCRADV to the ignition timing calculated based on the engine speed and the coolant temperature during hot restart.   4. The engine ignition timing control device according to claim 3, wherein the ignition timing calculation means corrects the coefficient KCRADV in the retard direction as the number of combustions after the start increases at the time of non-hot restart.   The engine ignition timing control device according to claim 3, wherein the ignition timing calculation means corrects the coefficient KCRADV in the retard direction when the number of combustions after the start exceeds a reference value at the time of non-hot restart.   4. The engine ignition timing according to claim 3, wherein the ignition timing calculation means corrects the coefficient KCRADV in the retarded direction by a predetermined change amount after the number of combustions after the start exceeds a reference value at the time of non-hot restart. Control device.   The engine ignition timing according to any one of claims 5 to 7, wherein the ignition timing calculating means corrects the coefficient KCRADV by limiting a value (KCRADVIN #) set as a retardation correction amount at the time of hot restart. Control device. The engine is a spark-ignition multi-cylinder engine, and is based on cylinder determination means for determining a cylinder position, a fuel injection valve provided for each intake passage of each cylinder, and signals from the start detection means and cylinder determination means. The engine ignition timing according to claim 1 or 3, further comprising injection control means for injecting fuel in synchronism with the cylinder determination timing for each cylinder or each cylinder group at the time of the first cylinder determination after the start of starting. Control device.

Images