JP2004197702A - Engine ignition timing control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avert excessive spark advance of an engine compared with a cylinder temperature level, which occurs upon the restart of the engine when only an inner cylinder temperature has risen, while a cooling water temperature has not increased much, because the initial advance angle is set at a low water temperature level in such a condition. <P>SOLUTION: The ignition timing on the occasion of engine startup is calculated based on the engine cooling water temperature. On this occasion, in the event of hot restart, when the restart-time inner cylinder temperature is higher than the cooling water temperature, the ignition time for engine startup is corrected so as to cause a delay in spark advance. Under this arrangement, it is possible to avert excessive spark advance when changes in the cooling water temperature are little despite the rising of the inner-cylinder temperature and to set suitable ignition timing. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ignition timing control device for a spark ignition type engine.
[0002]
[Prior art]
BACKGROUND ART As an ignition timing control device of a spark ignition type engine, there is known an ignition timing control device as shown in Patent Document 1. The ignition timing control is generally controlled using the engine speed and the cooling water temperature as parameters, but in the above-described prior art, a basic ignition timing determined based on the water temperature in consideration of the in-cylinder temperature change after starting is set to the basic ignition timing after the first explosion The correction process is performed so that the advance amount decreases as the elapsed time increases. This corresponds to the inconvenience that the cooling water temperature does not immediately follow the in-cylinder temperature change, but causes a deviation from the optimal ignition timing, even though the optimum ignition timing changes with the rise in the in-cylinder temperature.
[0003]
[Patent Document 1] Japanese Patent Application Laid-Open No. 2001-82302
[Problems to be solved by the invention]
However, in the prior art, since the basic advance value determined using the cooling water temperature at the beginning of the start is corrected according to the elapsed time from the first explosion, there is a problem that an appropriate ignition timing is not necessarily obtained at the time of restart. . In other words, when the engine is restarted with only the in-cylinder temperature rising and the cooling water temperature not rising so much, such as when the engine stalls immediately after a complete explosion or when the engine is restarted, the initial advance amount is reduced. Since the water temperature is set at a low temperature, the cylinder temperature becomes excessively advanced.
[0005]
Summary of the Invention
In the present invention, the ignition timing at the time of starting 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 higher than the cooling water temperature, the ignition timing at the start is retarded. This makes it possible to set an appropriate ignition timing while avoiding an over-advanced ignition timing when the change in the coolant temperature is small even though the in-cylinder temperature is rising.
[0006]
Hot restart can also be determined by directly detecting the cooling water temperature and the in-cylinder temperature.However, the cooling water temperature at the start is higher than the cooling water temperature at the time of shutdown before starting, and the number of combustions since the previous operation was started. May be determined as a condition that is greater than or equal to a predetermined reference value.
[0007]
BEST MODE FOR CARRYING OUT 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 a cylinder is determined at the time of start cranking and fuel is supplied in synchronization with an intake stroke or an exhaust stroke of the determined cylinder or cylinder group.
[0008]
FIG. 1 shows a schematic configuration of a four-stroke gasoline engine according to the present embodiment. In the figure, an intake pipe 3 of an engine 2 is provided with an air flow meter 4 for detecting an intake air amount and a throttle valve 5, and a fuel injection valve 8 is provided at an intake port 7 near a cylinder 6. The fuel injection valve 8 is provided for each cylinder. The fuel is supplied to the fuel injection valve 8 at a constant pressure by a fuel supply system (not shown), and the fuel is injected in an amount 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 opening time of the fuel injection valve 8.
[0009]
Reference numeral 9 denotes a crank angle sensor for detecting the rotation angle of the crank shaft 10 and the engine speed, and outputs a pulse-like POS signal and a REF signal. The POS signal is output for each unit rotation angle of the crankshaft 10, for example, at a cycle of one degree, 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. The controller 1 supplies an ignition signal to the ignition coil 14 at a predetermined timing and drives a starter motor (not shown) when the starter contact is turned on. Reference numeral 15 denotes a water temperature sensor that detects a cooling water temperature as a representative value of the engine temperature, and 16 denotes an oxygen sensor that detects an 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 a crank angle sensor 9, a water temperature signal from a water temperature sensor 15, and an oxygen sensor 16 And the like, and the fuel injection amount and the ignition control amount are calculated based on these.
[0011]
FIG. 2 is a block diagram showing functions of the controller 1 relating to fuel injection control and ignition control. The cranking determination section a determines the start of cranking based on the starter signal and the ignition signal from the ignition switch 13. The cylinder determination unit b determines the stroke of a certain cylinder of the engine 2 based on the PHASE signal from the cam position sensor 11 and the POS signal from the crank angle sensor 9. The rotation speed generator c calculates the engine rotation speed from the generation cycle 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 amount of intake air and the number of revolutions, and this is corrected by a water temperature signal or an oxygen concentration signal to operate at an intended air-fuel ratio. Is determined as described above. The drive signal output unit e outputs a drive signal for the fuel injection valve 8 based on the injection amount command value. When performing the injection by the injection end timing management, the injection start timing calculation unit f calculates the injection start timing from the injection pulse width and the engine speed, 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 POS signal or the rotation speed based on 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. Meanwhile, a primary current is output to the ignition coil according to the calculated ignition timing and energization angle.
[0012]
Next, based on the flowcharts shown in FIG. 3 and thereafter, the fuel injection control at the time of starting under the above-described configuration will be described first. 3 and 4 show a processing routine of the start control periodically executed by the controller 1, and FIG. 5 is a timing chart showing the state of the ignition timing and the like by the start control with time. The symbol S in the flowchart represents a processing step.
[0013]
In FIG. 3, first, in step 1, the state of the ignition switch is checked. When the ignition switch is turned off, or when the ignition switch is turned off from on, the correction coefficient KCRADV for the ignition timing at the time of starting is initialized to 1, and the current process ends. When the ignition switch is ON, the process proceeds to the starting time ignition timing setting processing of step 2 and subsequent steps. In step 2, the setting of the basic ignition timing at the start and the determination as to whether or not a hot restart condition is made are executed by the processing shown in FIG.
[0014]
In FIG. 4, in step 1, the cooling water temperature TWINT at the time of starting is read, and a basic ignition timing corresponding to the cooling water temperature is set by searching a table. The table gives general ignition timing characteristics to the cooling water temperature, and is set such that the lower the water temperature, the more the ignition timing is advanced. Next, in step 2, it is determined whether or not a hot restart has occurred. Here, the hot restart is a restart in a state where the temperature of the cooling water has hardly increased as compared with the time of the cold start, but the temperature in the cylinder has increased due to a certain combustion history. In this determination, the cooling water temperature TWNKO when the previous operation was stopped due to stall or engine stop operation is compared with the TWINT at the time of this start, and when TWINT is lower than TWNKO, or the number of combustions during the previous operation is the reference. If it is less than the value, a non-hot restart is performed (step 3), and if TWNKO ≧ TWINT and the previous number of times of combustion is equal to or more than the reference value, it is determined that a hot restart is performed (step 4). The number of times of combustion is calculated from the number of ignition signals after the complete explosion of the engine and the engine speed, and stored in the controller. As the determination reference value for the number of times of combustion, for example, the number of times of combustion that causes in-cylinder temperature change that requires correction of the ignition timing is checked in advance for the engine, and the result is stored in the controller.
[0015]
In FIG. 3, according to the determination result, when it is a non-hot restart, first, in step 6, the number of combustions REFCNTS after the start is compared with a reference value KCRADV1 #, and when REFCNTS ≧ KCRADV1 #, 100 ms thereafter. After each elapse, a value obtained by subtracting a predetermined small change amount DKCRADV # from the correction coefficient KCRADV is newly updated as KCRADV, and then the process proceeds to step 4 in which the starting ignition timing TADVM is set. The KRADV reduction correction is executed with a predetermined retard 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 restart is a hot restart, the process proceeds to step 4 after substituting the retardation correction value KCRADVIN # for the correction coefficient KCRADV in step 3.
[0017]
In step 4, the starting basic ignition timing read from the water temperature table is subjected to rotation speed correction and correction by the coefficient KCRADV to calculate the starting ignition timing TADVM. As described above, the water temperature table gives a basic ignition timing having a characteristic of advancing as the water temperature becomes lower. 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 is initially set to 1 at the time of non-hot restart, and the starting is performed by the normal ignition timing setting in which the basic ignition timing is corrected by the number of revolutions. Therefore, the ignition timing is corrected in the retard direction in accordance with the rise in the cylinder temperature. As a result, an appropriate ignition timing is set in accordance with the in-cylinder temperature rise after the start at the cold start. On the other hand, at the time of hot restart, the ignition timing is corrected in the retard direction from the beginning of the start by KCRADVIN #. As a result, an appropriate ignition timing can be obtained even when the in-cylinder temperature is high from the start. In this way, operation can be performed at the highest torque point regardless of the in-cylinder temperature state. At the time of a hot start, that is, at the time of starting in a state where the engine has been completely warmed up and the cooling water temperature has sufficiently risen, it is not necessary to perform the correction at the time of the hot restart as described above. Thus, the ignition timing corresponding to the in-cylinder temperature state can be obtained from the beginning of the start.
[0019]
FIG. 5 shows a timing chart of this control. The ignition timing characteristic indicated by the solid line in the figure indicates the time of non-hot restart determination.In response to the fact that the temperature in the combustion chamber increases after starting and the required ignition timing is retarded, an alternative parameter of the in-cylinder temperature is used. The ignition timing is delayed by gradually decreasing the ignition timing correction coefficient KCRADV when the number of combustion exceeds a predetermined value. The dashed line is a characteristic at the time of hot restart determination, and the ignition timing is a set value that is previously retarded from the basic ignition timing by KCRADVIN #. In the drawing, reference numerals IGN and StartSW are an ignition switch and a starter switch, respectively, 1 indicates an ON state, and 0 indicates an OFF state.
[0020]
As in the case of the engine assumed in the present embodiment, when the sequential fuel injection is performed from the start to reduce the emission and the supply fuel amount is adjusted appropriately, the ignition timing is appropriately set as described above. The effect can be maximized. In other words, the richer the air-fuel ratio is, the more the required ignition timing is retarded, and conversely, by advancing it, the air-fuel ratio can be made lean for the same torque. This is because torque required for starting can be obtained with a minimum amount of fuel.
[0021]
In the above embodiment, the hot restart determination is made based on the change in the cooling water temperature and the combustion history. By doing so, it is possible to make a hot restart determination.
[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 a starting ignition timing control executed by the controller.
FIG. 4 is a second flowchart of the starting ignition timing control executed by the controller.
FIG. 5 is a timing chart at the time of normal water temperature control of the starting control.
[Explanation of symbols]
DESCRIPTION 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 (10)

In a spark ignition type engine having an ignition timing calculating means for calculating an ignition timing at the time of starting based on an engine coolant temperature,
The ignition timing calculating means is configured to delay-correct the ignition timing at the time of the start at the time of a hot restart in which the in-cylinder temperature at the time of the start is higher than the coolant temperature. Timing control device. 2. The engine ignition timing control device according to claim 1, wherein the ignition timing calculation means delays the ignition timing calculated based on the engine speed and the coolant temperature at the time of hot restart. In a spark ignition type engine having an ignition timing calculating means for calculating an ignition timing at the time of starting based on an engine coolant temperature,
In the ignition timing calculation means, a correction calculation expression having a coefficient KCRADV for correcting the ignition timing at the time of starting is set, and the KCRADV is a hot spring in which the in-cylinder temperature at startup is higher than the cooling water temperature. An ignition timing control device for an engine, wherein the ignition timing at the start is corrected in the retard direction at the time of starting compared with the time of non-hot restart. 4. The engine ignition timing control device according to claim 3, wherein the ignition timing calculation means applies a correction coefficient KCRADV to the ignition timing calculated based on the engine speed and the coolant temperature at the time of a hot restart to retard the ignition timing. 4. The ignition timing control device for an engine according to claim 3, wherein the ignition timing calculation means corrects the coefficient KCRADV in a retard direction with an increase in the number of times of combustion after the start during non-hot restart. 4. The ignition timing control device for an engine according to claim 3, wherein the ignition timing calculation means corrects the coefficient KCRADV in a retard direction when the number of combustions after starting exceeds a reference value during a non-hot restart. The ignition timing of the engine according to claim 3, wherein the ignition timing calculation means corrects the coefficient KCRADV in a retard direction by a predetermined change after the number of combustions after starting exceeds a reference value at the time of non-hot restart. Control device. The ignition timing of the engine according to any one of claims 5 to 7, wherein the ignition timing calculation means corrects the coefficient KCRADV by limiting a value (KCRADVIN #) set as a retard correction amount at the time of hot restart. Control device. The ignition timing calculating means performs a hot restart when the cooling water temperature at the start is higher than the cooling water temperature at the time of operation stop before the start and the number of combustions after the start at the previous operation is equal to or more than a predetermined reference value. The engine ignition timing control device according to claim 1 or 3, wherein the determination is performed. The engine is a spark ignition type multi-cylinder engine, 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 the cylinder determination means. The ignition timing of the engine according to claim 1 or 3, further comprising: injection control means for injecting fuel in synchronization with the cylinder determination timing for each cylinder or each cylinder group at the time of the first cylinder determination after the start of the start. Control device.

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