JP3863362B2 - Control device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control device for an internal combustion engine that determines a fuel property level when starting the internal combustion engine and reflects the determination result in fuel injection control or the like.
[0002]
[Prior art]
As a conventional technique of this type, for example, “engine fuel injection device” disclosed in Japanese Patent No. 2833020 is known. The device of the publication pays attention to the behavior of the rotational speed at the time of engine start, measures the peak value of the idle speed after the engine is started, determines the fuel property based on the peak value, or idles after the engine is started. The time until the number reaches the peak value is measured, and the fuel property is determined based on the time.
[0003]
As a result, according to the behavior of the engine speed, the fuel properties such as whether the fuel (gasoline) to be used is heavy gasoline or light gasoline can be correctly determined, and as a result, the fuel injection control is suitably performed.
[0004]
[Problems to be solved by the invention]
However, the peak rotational speed after starting the engine has a large variation in itself, and the tendency becomes more prominent as the fuel property becomes heavier. That is, for example, in the case of heavy fuel, unexpected misfire is likely to occur, and the peak rotational speed varies due to this. At this time, the intake pipe negative pressure fluctuates, the evaporation rate of the injected fuel by the injectors varies, the air-fuel ratio varies, and the engine speed becomes unstable.
[0005]
Therefore, in the case of the prior art disclosed in the above publication, there is a possibility that the fuel property level may be erroneously determined, which causes a problem that the controllability of the fuel injection control deteriorates.
[0006]
The present invention has been made paying attention to the above problems, and an object of the present invention is to provide a control device for an internal combustion engine that can solve the conventional problems and can accurately determine the fuel properties.
[0007]
[Means for Solving the Problems]
Claim 1 , 13 In the invention described in the above, at the time of idling after the start of the internal combustion engine, the rotational speed control means for performing the rotational speed feedback control so as to converge the rotational speed of the internal combustion engine to the target rotational speed, and the rotational speed feedback by the rotational speed control means Fuel property determining means for determining the fuel property according to the behavior of the control amount during control.
[0008]
According to this configuration, feedback control is performed so that the engine speed converges to the target value. Therefore, regardless of the fuel property level (volatility) of the fuel used, the engine speed and the intake pipe negative generated at that time are reduced. The pressure is stable and the evaporation rate of the injected fuel is stable without variation. At this time, under the state where the evaporation rate of the injected fuel is stabilized, the control amount at the time of the rotational speed feedback control differs depending on the fuel property level, so the fuel property is determined according to the behavior of this control amount. The fuel property can be determined with high accuracy.
[0009]
Claims 1 The invention described in the above item has the following characteristics on the premise that the ignition timing is feedback-controlled by the ignition timing control means so that the engine speed converges to the target speed. That is,
・ Claim 1 In the invention, the ignition timing control amount when the engine speed is stabilized with respect to the target speed at the time of feedback control by the ignition timing control means and the ignition timing control amount that converges after the rotation speed is stabilized are calculated, The fuel property is determined based on the difference between the ignition timing control amounts.
[0010]
Claims above 1 In this invention, for example, when the engine speed reaches the peak speed at the start of the engine and then once falls below the target speed, the ignition timing is controlled to the advance side to increase the speed. The ignition timing control amount at this time is a parameter for determining the fuel property. Even in such a case, since the ignition timing control amount differs depending on the fuel property level of the fuel used under the state where the rotational speed is stable, that is, the state where the evaporation rate is stable, the fuel depends on the behavior of this control amount. By determining the property, the fuel property can be accurately determined.
[0011]
The ignition timing control amount when the engine speed is stabilized with respect to the target speed is all the control amount required at the time of feedback of the engine speed, including the effect of fuel properties, but converges after the engine speed is stabilized. The ignition timing control amount to be performed is a control amount corresponding to a deviation of the internal combustion engine or a change with time. Therefore, particularly in the invention of claim 4, by determining the fuel property based on the above-described difference in the control amount, the influence due to the misalignment of the internal combustion engine and the change over time is canceled, and the accuracy of determining the fuel property is further improved. .
[0012]
On the other hand, Claim 13 In the invention described in the above, the intake air amount control by the intake air amount control means and the subsequent ignition timing control by the ignition timing control means are performed, and the engine speed is compared with the target speed during the feedback control by the ignition timing control means. The ignition timing control amount at the time of stabilization is corrected by the upper limit value of the intake control amount at the time of feedback control by the intake amount control means, and the fuel property is determined according to the corrected ignition timing control amount.
[0013]
Performing correction based on the upper limit value of the intake control amount means canceling the influence of the change over time by the intake amount control means from the ignition timing control amount that is a parameter for determining fuel properties. Therefore, the fuel property determination with higher accuracy can be performed.
[0018]
Meanwhile, claims 2 In the invention described in, at the time of idling after the internal combustion engine is started, feedback control is performed so that the engine speed converges to the target speed by intake air amount control and subsequent ignition timing control. The first determination means determines the ignition timing control amount when the engine speed is stabilized with respect to the target speed at the time of feedback control by the ignition timing control means, and the upper limit of the intake control amount at the time of feedback control by the intake amount control means. The fuel property is determined according to the corrected ignition timing control amount. The second determination means includes an ignition timing control amount when the engine speed is stabilized with respect to the target speed during feedback control by the ignition timing control means, and an ignition timing control quantity that converges after the rotation speed is stabilized. The fuel properties are determined based on the difference. Then, the fuel property determination by the first determination means is performed until the engine speed stabilizes with respect to the target speed and thereafter the ignition timing control amount converges. When the ignition timing control amount converges, the second determination is made. Shift to fuel property determination by means.
[0019]
This claim 2 According to the invention, after the engine is started, the first and second determination means are sequentially executed, and in each of the fuel property determination, the fuel property can be accurately determined based on the ignition timing control amount.
[0020]
Here, both the first and second determination means can determine the fuel property with higher accuracy than in the conventional apparatus. However, comparing these both determination means, the fuel property determination by the second determination means. Is somewhat more accurate. Therefore, by sequentially switching the first and second determination means as described above, when the engine speed is stabilized with respect to the target speed, and thereafter when the ignition timing control amount converges, The fuel properties can be determined by the most suitable method.
[0021]
Claims 3 As described in the above, there is further provided third determination means for determining the fuel property based on “peak speed” or “deviation between the peak speed and the target speed” at the time of starting the engine, and feedback by the ignition timing control means Before the engine speed is stabilized relative to the target speed during control, if the fuel property is determined by the third determining means, the ignition timing feedback control and intake air amount control are performed after the internal combustion engine is started. This eliminates the inconvenience that the fuel property cannot be determined during the period until the parameters for determining the fuel property are obtained.
[0022]
An apparatus for determining fuel properties according to an ignition timing control amount (claims) 1-3 Either One paragraph In the apparatus), it is conceivable that the degree of increase in the rotational speed (degree of torque increase) changes each time according to the amount of advancement of the ignition timing at that time. Therefore, if the advance amount of the ignition timing changes, the fuel property determination result is affected. Therefore, the claim 4 In the invention described in, the ignition timing control amount for use in determining the fuel property is corrected according to the advance angle of the ignition timing at that time. As a result, the fuel property determination with higher accuracy can be performed.
[0023]
Claim 5 In the invention described in (1), the determined fuel property is backed up before the operation of the internal combustion engine is stopped, and until the fuel property is newly determined at the next engine start, the backup fuel property determination value is read out. Use. Thus, after the internal combustion engine is started, the fuel property can be determined by substituting the backup value until the parameter for determining the fuel property is prepared.
[0024]
At this time, the claim 6 As described above, the newly determined fuel property is added to the fuel property determination value backed up during the previous operation while smoothing at a predetermined annealing rate, and the added value is determined as the fuel property determination value. Value. By performing the smoothing operation as described above, a control device suitable for practical use can be realized.
[0025]
Claim 7 In the invention described in (1), when a vehicle-mounted battery is newly connected to a memory for backing up a fuel property determination value, the smoothness of the newly determined fuel property is reduced initially. Here, reducing the degree of annealing means increasing the reflection rate of the current value so that the newly determined fuel property is quickly converged to the true value. As a result, the fuel property can be correctly determined even when the backup value disappears, such as during battery replacement.
[0026]
Claims 8 In the invention described in (1), immediately after the fuel supply, the smoothness degree of the newly determined fuel property is reduced. In this case, when it is considered that the fuel property changes due to refueling, the fuel property can be quickly converged to the true value, and the fuel property can be correctly determined.
[0027]
Claim 9 In the invention described in, the newly determined fuel property (current value) is smoothed by the fuel property determination value backed up during the previous operation, and the corrected value is used as the fuel property determination value. When the determination value of the fuel property by the determination means of 2 is made, the degree of smoothing is made smaller than when the determination value of the fuel property by the first determination means is made.
[0028]
In short, comparing the first and second determination means as described above, the second determination means has a somewhat higher accuracy of determination of the fuel property, so the degree of smoothing is reduced and the reflection rate of the current value is increased. To do. Further, when the fuel property determination value of the first determination means with relatively low accuracy is made, the degree of smoothing is somewhat increased and the reflection rate of the current value is decreased. As a result, the reliability of the fuel property determination result can be further improved.
[0029]
Further, the third determination means has a somewhat lower accuracy of determination of the fuel property than the first and second determination means. Therefore, claim 1 0 As described above, when the determination value of the fuel property by the third determination means is made, the degree of smoothing is made larger than when the determination value of the fuel property by the first or second determination means is made. Thereby, the reliability of the determination result of the fuel property is further improved.
[0030]
Claim 1 1 In the invention described in the above, when the idle state is released, or when the state of an electric load or the like changes before and after the start of feedback control by the ignition timing control means, the fuel property by the first or second determination means is changed. Since the determination is prohibited, the fuel property determination parameter is not erroneously recognized, and the reliability of the apparatus is improved.
[0031]
Claim 1 2 Applied to a fuel injection control system that performs a predetermined fuel injection amount increase when the internal combustion engine is started and during warm-up, and the degree of fuel injection amount increase is changed according to the determined fuel properties If so, the controllability of the fuel injection control is improved, and as a result, the exhaust emission can be improved.
[0032]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.
[0033]
The apparatus of the present embodiment is embodied as a fuel injection control system that optimally controls the fuel injection amount at the start-up and warm-up of a gasoline-injection multi-cylinder internal combustion engine (hereinafter referred to as the engine). An injector for injecting and supplying fuel to each cylinder is controlled by an electronic control unit (hereinafter referred to as an ECU) having a microcomputer as a main component. In particular, the ECU determines the fuel properties of the fuel to be used when the engine is started, and suitably controls the fuel injection amount according to the determination result. The system will be described in detail below.
[0034]
FIG. 1 is a configuration diagram showing an outline of an engine control system according to the present embodiment. In FIG. 1, an intake pipe 2 and an exhaust pipe 3 are connected to the engine 1. The intake pipe 2 is provided with a throttle valve 4, and the opening degree of the throttle valve 4 is controlled by driving a throttle actuator 5. The throttle valve 4 is provided with a throttle opening sensor 6, and the surge tank 7 of the intake pipe 2 is provided with an intake pressure sensor 8.
[0035]
A piston 10 is disposed in the cylinder 9, and a combustion chamber 13 above the piston 10 communicates with the intake pipe 2 and the exhaust pipe 3 via an intake valve 14 and an exhaust valve 15. The exhaust pipe 3 is provided with an A / F sensor 16 composed of a limit current type air-fuel ratio sensor, and the A / F sensor 16 is an oxygen concentration (or carbon monoxide which is an unburned gas) in the exhaust gas. A linear and linear air-fuel ratio signal is output in proportion to The cylinder 9 (water jacket) is provided with a water temperature sensor 21 for detecting the cooling water temperature.
[0036]
The intake port 17 of the engine 1 is provided with an electromagnetically driven injector 18 for each cylinder. The injector 18 injects fuel (gasoline) supplied from a fuel tank (not shown). A spark plug 19 is disposed on the cylinder head 12. The rotation of a crankshaft (not shown) accompanying combustion is detected by a rotation speed sensor 20.
[0037]
The ECU 30 is mainly composed of a microcomputer including a CPU 31, a ROM 32, a RAM 33, a backup RAM 34, and the like. Each detection signal is input to the ECU 30 from the throttle opening sensor 6, the intake pressure sensor 8, the A / F sensor 16, the rotation speed sensor 20, the water temperature sensor 21, and the like, and the ECU 30 determines the throttle based on each detection signal. The opening, intake pressure, air-fuel ratio (A / F), engine speed, and engine water temperature are detected.
[0038]
The CPU 31 that performs various calculations in accordance with the program in the ROM 32 calculates the optimum fuel injection amount, ignition timing, and intake air amount based on the engine operating state at that time, and controls the injector 18, ignition by a control signal corresponding to the calculation result. The drive of the plug 19 and the throttle actuator 5 is controlled. Further, when starting the engine, the CPU 31 performs feedback (F / B) control of the engine speed to the target idle speed, determines the fuel property level, and corrects the fuel injection amount based on the fuel property level. The backup RAM 34 is a memory that holds the stored contents even when the ignition switch is turned off by power supply from a battery (not shown), and stores and holds the fuel property level determined by the CPU 31 as a learning value.
[0039]
Next, the operation of the present control system will be described. First, the outline of the rotational speed F / B control by the CPU 31 will be described with reference to the time chart of FIG. FIG. 2 shows the behavior of the engine speed Ne and the transition of various control amounts when the engine is started.
[0040]
The engine speed Ne suddenly increases as the engine starts, reaches a peak speed Npk at time t1, then starts to decrease, and temporarily falls below the target idling engine speed (target speed Nt) at time t2. . It is generally known that the peak rotational speed Npk varies depending on the fuel properties. The higher the fuel is heavy gasoline (the lower the volatility), the smaller the peak rotational speed Npk. The target rotation speed Nt is an idle rotation speed set according to the engine water temperature or the like, and is set to 1200 rpm as an example.
[0041]
At time t2, intake F / B control for converging the engine speed Ne to the target speed Nt is started. That is, the intake F / B amount qi is calculated according to the difference (revolution number deviation ΔN) between the engine rotational speed Ne and the target rotational speed Nt at that time, and the throttle actuator 5 is operated based on the intake F / B amount qi. Driven and the intake air amount is increased.
[0042]
At the time t3 after the start of the intake F / B control, the intake F / B amount qi reaches the upper limit value qiMAX, and therefore no further increase in the intake amount is performed. Instead, the ignition timing F / B control is started. The That is, the ignition timing F / B amount ai is calculated according to the rotational speed deviation ΔN, and the ignition timing is controlled based on the ignition timing F / B amount ai. After time t3, the ignition timing is controlled to the advance side by the ignition timing F / B amount ai. By this ignition timing F / B control, the engine speed Ne gradually converges to the target speed Nt.
[0043]
After that, at time t4, the engine speed Ne almost converges to the target speed Nt and stabilizes. When the engine rotational speed Ne is stabilized in this way, the ignition timing F / B amount ai at that time is calculated as the maximum ignition timing F / B amount (maximum value aiMAX) required for rotational speed stabilization. Then, “1” is set to the maximum value calculation completion flag xaiMAX indicating that the maximum value aiMAX of the ignition F / B amount has been calculated.
[0044]
Thereafter, the ignition timing F / B amount ai is gradually returned to the retard side. At time t5, it is considered that the ignition timing F / B amount ai has converged, and the ai value at that time is calculated as the minimum value aiMIN. Then, “1” is set to the minimum value calculation completion flag xaiMIN indicating that the minimum value aiMIN of the ignition F / B amount has been calculated.
[0045]
It should be noted that the fuel increase is performed supplementarily during the period Ta in which the advance amount of the ignition timing F / B amount ai is greater than or equal to a predetermined value (for example, advance angle 5 ° CA). Thereby, generation | occurrence | production of misfire is suppressed.
[0046]
Next, the rotation speed F / B control procedure and the fuel property level determination procedure by the CPU 31 will be described with reference to the flowcharts of FIGS.
FIG. 3 is a flowchart showing an outline of the rotational speed F / B control at the time of engine start, and this process is executed by the CPU 31 at predetermined intervals. In FIG. 3, in step 110, after the engine speed Ne has reached the peak speed Npk, it is determined whether or not it has become equal to or less than the target speed Nt. Set XFBON to “1”. In the following step 114, it is determined whether or not XFBON = 1. Then, under the condition that XFBON = 1, the F / B control of the intake or ignition timing after step 120 is performed.
[0047]
That is, in step 120, it is determined whether or not the intake F / B amount qi by the intake F / B control is less than a predetermined upper limit qiMAX. Here, the upper limit value qiMAX is set in accordance with, for example, the peak rotation speed Npk or the deviation (Npk−Nt) between the peak rotation speed Npk and the target rotation speed Nt using the relationship shown in FIG. The upper limit qiMAX is set to a higher value as the peak rotational speed Npk is higher or the deviation (Npk−Nt) is larger.
[0048]
If qi <qiMAX (step 120 is YES), the intake F / B control is performed at step 130. In this intake F / B control, as shown in FIG. 4A, the engine speed Ne is subtracted from the target engine speed Nt to obtain the engine speed deviation ΔN (step 131). / B correction term kqi is calculated (step 132). Further, the calculated F / B correction term kqi is added to the previous value of the intake F / B amount qi, and the sum is taken as the current value of the intake F / B amount qi (step 133).
[0049]
Returning to FIG. 3, if the intake F / B amount qi has reached the upper limit value qiMAX (step 120 is NO), the process proceeds to step 140, and the upper limit value qiMAX of the intake F / B control is stored in the RAM 33.
[0050]
Thereafter, in step 150, ignition timing F / B control is performed. In this ignition timing F / B control, as shown in FIG. 4B, the engine speed Ne is subtracted from the target engine speed Nt to obtain the engine speed deviation ΔN (step 151), and according to the engine speed deviation ΔN. An F / B correction term kai is calculated (step 152). Further, the calculated F / B correction term kai is added to the previous value of the ignition timing F / B amount ai, and the sum is set as the current value of the ignition timing F / B amount ai (step 153).
[0051]
After execution of step 150, in step 160, fuel increase is performed according to the ignition timing F / B amount ai. In this fuel increase processing, for example, using the relationship shown in FIG. 13, a fuel increase coefficient is obtained according to the ignition timing F / B amount ai, and the fuel injection amount is increased and corrected by the fuel increase coefficient. In the relationship shown in FIG. 13, the area up to the predetermined advance angle (5 ° CA) is a dead zone.
[0052]
In the intake F / B control and the ignition timing F / B control, the F / B correction terms kqi and kai are the sum of the proportional term (p term) and the integral term (i term), or the proportional term itself. Also good.
[0053]
According to the process in FIG. 3, the intake F / B control is performed in the period from time t2 to t3 in FIG. 2, and after time t3, the upper limit qiMAX of the intake F / B control is maintained and the ignition timing F / B is maintained. B control is performed. Further, the fuel increase is performed in the period Ta in FIG.
[0054]
Next, the procedure for determining the fuel property level will be described with reference to the flowcharts of FIGS.
First, in step 201 of FIG. 5, it is determined whether or not the engine water temperature Tw is equal to or lower than a predetermined temperature (70 ° C. in the present embodiment). If NO, the process is terminated. That is, in a warm-up state of the engine (Tw> 70 ° C.), the difference in fuel property level is unlikely to appear in the behavior of the engine operation, so the subsequent fuel property determination is not performed.
[0055]
In step 202, it is determined whether or not the detection of the peak rotational speed Npk has already been completed. When step 202 is NO, the process proceeds to step 203, and the learning value KL stored in the backup RAM 34 is determined as the main determination value for determining the fuel property level. In this case, this determination value is used to correct the transient fuel injection amount for performing acceleration increase and the asynchronous injection amount for performing all cylinder injection according to the change amount of the throttle opening (step 208). Thereafter, if the ignition switch is not turned off, the process is temporarily terminated.
[0056]
On the other hand, when both steps 201 and 202 are YES, the first fuel property determination value KN1, the second fuel property determination value KN2, and the third fuel property determination value KN3 are calculated in the procedure after step 204.
[0057]
That is, in step 204, it is determined whether or not the second fuel property determination value KN2 has already been calculated. In subsequent step 205, it is determined whether or not the first fuel property determination value KN1 has already been calculated. Determine. If both KN1 and KN2 have not been calculated, the routine proceeds to step 300, where the first fuel property determination value KN1 is calculated based on the deviation ΔNpt between the peak rotational speed Npk and the target rotational speed Nt.
[0058]
In the subsequent step 400, the ignition timing F / B amount ai by the processing of FIG. 4B is monitored, and the maximum value aiMAX is calculated. However, details of steps 300 and 400 will be described later.
[0059]
Thereafter, in step 206, it is determined whether or not the maximum value aiMAX of the ignition timing F / B amount has already been calculated, and whether or not there is a state change before and after the start of the ignition timing F / B control. Completion of aiMAX calculation is determined by the maximum value calculation completion flag xaiMAX. Further, when determining the state change, the ignition timing F / B control is compared before and after the start,
・ When load conditions such as electric load, air conditioner, power steering, etc. have not changed,
・ When the idle state is not released,
・ When the shift position of the transmission is not operated to the drive position,
It is determined that there is no state change.
[0060]
Immediately after the calculation of the KN1 value in step 300, since the aiMAX value has not been calculated, step 206 becomes NO, and in the subsequent step 207, the calculated first fuel property determination value KN1 is determined as the main determination value. . At this time, when the learning value KL is determined as the main determination value in the previous step 203, the learning value KL is updated with the first fuel property determination value KN1. Then, the transient fuel injection amount and the asynchronous injection amount are corrected using the determination value (KN1) (step 208).
[0061]
When the first fuel property determination value KN1 is calculated as described above, the next time this process is executed, step 205 becomes YES, step 300 is skipped, and the process proceeds to step 400. When the maximum value aiMAX of the ignition timing F / B amount is calculated and it is determined that there is no state change (step 206 is YES), the routine proceeds to step 500 in FIG. 6 and the maximum value of the ignition timing F / B amount is reached. Based on aiMAX, a second fuel property determination value KN2 is calculated.
[0062]
In the subsequent step 600, the ignition timing F / B amount ai by the process of FIG. 4B is monitored, and the minimum value aiMIN is calculated. However, details of steps 500 and 600 will be described later.
[0063]
Thereafter, in step 211, it is determined whether or not the minimum value aiMIN of the ignition timing F / B amount has already been calculated and whether or not there is a state change before and after the start of the ignition timing F / B control. Completion of calculation of aiMIN is determined by a minimum value calculation completion flag xaiMIN.
[0064]
Immediately after the calculation of the KN2 value in step 500, the aiMIN value has not been calculated, so step 211 is NO, and in the subsequent step 212, the calculated second fuel property determination value KN2 is determined as the main determination value. . At this time, if the first fuel property determination value KN1 is determined as the main determination value in the previous step 207, the KN1 is updated with the second fuel property determination value KN2. Then, the transient fuel injection amount and the asynchronous injection amount are corrected using the determination value (KN2) (step 208 in FIG. 5).
[0065]
When the second fuel property determination value KN2 is calculated as described above, the next time this process is executed, step 204 in FIG. 5 becomes YES, and the process directly proceeds to step 600 in FIG. Then, when the minimum value aiMIN of the ignition timing F / B amount is calculated and it is determined that there is no state change (step 211 is YES), the process proceeds to step 700 and based on the amount of change in the ignition timing F / B amount. A third fuel property determination value KN3 is calculated. Details of step 700 will also be described later.
[0066]
In the following step 213, the third fuel property determination value KN3 is determined as the main determination value. At this time, if the second fuel property determination value KN2 is determined as the main determination value in the previous step 212, the KN2 is updated with the third fuel property determination value KN3. Then, the transient fuel injection amount and the asynchronous injection amount are corrected using the determination value (KN3) (step 208 in FIG. 5).
[0067]
When the ignition switch is turned off (YES in step 209 in FIG. 5), the main determination value (fuel property determination value) at that time is stored in the backup RAM 34. However, the timing for backing up this determination value is not limited to when the ignition switch is turned off, and may be after the third fuel property determination value KN3 is calculated.
[0068]
5 and 6, in the time chart of FIG.
Before the time t1, the learning value KL in the backup RAM 34 becomes the main determination value. In the period from time t1 to t4, the first fuel property determination value KN1 becomes the main determination value. In the period from time t4 to t5. The second fuel property determination value KN2 becomes the main determination value, and after time t5, the third fuel property determination value KN3 becomes the main determination value.
[0069]
FIG. 7 is a flowchart showing in detail the calculation procedure of the first fuel property determination value KN1 in step 300 of FIG. In step 301, a deviation ΔNpt between the peak rotational speed Npk and the target rotational speed Nt is calculated (ΔNpt = Npk−Nt). In the subsequent step 302, the fuel property coefficient F1 is calculated according to the rotational speed deviation ΔNpt. The fuel property coefficient F1 is obtained by map search. For example, when the rotational speed deviation ΔNpt is small, the fuel property coefficient F1 is regarded as heavy fuel and the fuel property coefficient F1 is set to a relatively large value.
[0070]
Thereafter, in step 303, it is determined whether the battery is immediately after being turned on (immediately after replacement) or just after gasoline refueling. That is, immediately after the battery is turned on (immediately after replacement), the learning value KL in the backup RAM 34 is cleared (KL = 1.0), so it is necessary to increase the learning speed of the fuel property, and gasoline refueling Immediately after, it is necessary to increase the learning speed of the fuel property. Therefore, when step 303 is YES, the smoothing ratios sma and smb are set so as to reduce the degree of smoothing for the fuel property coefficient F1 calculated this time (step 305), and when step 303 is NO, normal The smoothing ratios sma and smb are set so as to perform the smoothing calculation with the smoothing degree (step 304). The presence or absence of gasoline refueling may be determined from the detected value of the level gauge in the fuel tank or the detected value of the cap sensor provided at the fuel filler port of the fuel tank.
[0071]
Thereafter, in step 306, from the fuel property coefficient F1 calculated this time, the learned value KL at the previous operation, and the respective annealing rates sma and smb, the following equation (1):
KN1 = (F1 × sma) + (KL × smb) (1)
Is used to calculate the first fuel property determination value KN1.
[0072]
FIG. 8 is a flowchart showing a procedure for calculating the maximum value of the ignition timing F / B amount in step 400 of FIG. The process of FIG. 8 is a process of obtaining an average value avai of the ignition timing F / B amount for a predetermined period (for example, 1 second) and calculating a maximum value aiMAX from the average value avai. The average value avai is set to the previous value avai0. In the subsequent step 402, an average value avai of the ignition timing F / B amount is newly calculated. For example, the ignition timing F / B amount ai by the process of FIG. 4B is integrated for 1 second, and the integrated value is divided by unit time to calculate the average value avai of the ignition timing F / B amount.
[0073]
Thereafter, in step 403, the previous value avai0 of the average value of the ignition timing F / B amount is compared with the current value avai. If avai0 ≧ avai, the routine proceeds to step 404, where the absolute value of the rotational speed deviation ΔN (= Nt−Ne) between the target rotational speed Nt and the engine rotational speed Ne becomes less than a minute predetermined value Nb, and the engine rotational speed Ne. Determines whether or not has converged to the target rotational speed Nt.
[0074]
If step 404 is YES, it is considered that the engine speed Ne is stabilized with respect to the target speed Nt, and in step 405, the average value avai0 of the previous ignition timing F / B amount is set to the maximum of the ignition timing F / B amount. The value aiMAX is set, and in the subsequent step 406, “1” is set to the maximum value calculation completion flag xaiMAX.
[0075]
FIG. 9 is a flowchart showing in detail the procedure for calculating the second fuel property determination value KN2 in step 500 of FIG. In step 501, a correction term aihs is calculated by multiplying the upper limit qiMAX in the intake F / B control by a predetermined conversion coefficient f (aihs = f · qiMAX). In the subsequent step 502, the maximum ignition timing F / B amount is calculated. The change amount Δai1 of the ignition timing F / B amount is calculated by adding the value aiMAX and the calculated correction term aihs (Δai1 = aiMAX + aihs).
[0076]
In step 503, the fuel property coefficient F2 is calculated according to the change amount Δai1 of the ignition timing F / B amount. The fuel property coefficient F2 is obtained by map search. As the change amount Δai1 is larger, the fuel property coefficient F2 is regarded as a heavy fuel, and the fuel property coefficient F2 is set to a relatively large value.
[0077]
Thereafter, in step 504, it is determined whether it is immediately after turning on the battery (immediately after replacement) or immediately after gasoline refueling. When step 504 is NO, the smoothing ratios sma and smb are set so that the smoothing calculation is performed with the normal smoothing degree (step 505). When step 504 is YES, the fuel calculated this time The smoothing rates sma and smb are set so as to increase the learning speed by reducing the degree of smoothing for the property coefficient F2 (step 506).
[0078]
Thereafter, in step 507, the following equation (2) is calculated from the fuel property coefficient F2 calculated this time, the learned value KL at the previous operation, and the respective annealing rates sma and smb:
KN2 = (F2 × sma) + (KL × smb) (2)
Is used to calculate the second fuel property determination value KN2.
[0079]
FIG. 10 is a flowchart showing the procedure for calculating the minimum value of the ignition timing F / B amount in step 600 of FIG. In step 601, it is determined whether or not a maximum value calculation completion flag xaiMAX is “1”. When xaiMAX = 1, in step 602, the previously calculated average value avai is set as the previous value avai0. In the subsequent step 603, an average value avai of the ignition timing F / B amount is newly calculated. For example, the ignition timing F / B amount ai by the process of FIG. 4B is integrated for 1 second, and the integrated value is divided by unit time to calculate the average value avai of the ignition timing F / B amount.
[0080]
Thereafter, in step 604, it is determined whether or not 5 seconds have elapsed after the calculation of the maximum value aiMAX of the ignition timing F / B amount. In subsequent step 605, whether or not 20 seconds have elapsed since the calculation of aiMAX. Is determined. If step 604 is YES and step 605 is NO, the process proceeds to step 606, where the previous value avai0 of the average value of the ignition timing F / B amount is compared with the current value avai. If avai0 ≦ avai, the previous value avai0 is set to the minimum value aiMIN of the ignition timing F / B amount in step 607.
[0081]
If avai0> avai (NO in step 606), it is determined in step 608 whether the average value avai of the ignition timing F / B amount has converged. For example, if the difference between the current value of the average value avai and the previous value is less than a predetermined value that is sufficiently small, the avai value is considered to have converged, and the process proceeds to step 609 to determine the current average value avai as the ignition timing F / B amount. The minimum value is aiMIN.
[0082]
Further, even when 20 seconds have elapsed after the calculation of aiMAX (YES in step 605), in step 609, the current average value avai is set to the minimum value aiMIN of the ignition timing F / B amount. After the calculation of the aiMIN value, in step 610, “1” is set to the minimum value calculation completion flag xaiMIN.
[0083]
FIG. 11 is a flowchart showing in detail the procedure for calculating the third fuel property determination value KN3 in step 700 of FIG. In step 701, the change amount Δai2 of the ignition timing F / B amount is calculated from the difference between the maximum value aiMAX and the minimum value aiMIN of the ignition timing F / B amount (Δai2 = aiMAX−aiMIN).
[0084]
Thereafter, in step 702, the fuel property coefficient F3 is calculated according to the change amount Δai2 of the ignition timing F / B amount. The fuel property coefficient F3 is obtained by map search. As the change amount Δai2 is larger, the fuel property coefficient F3 is regarded as a heavy fuel and the fuel property coefficient F3 is set to a relatively large value.
[0085]
Thereafter, in step 703, it is determined whether it is immediately after turning on the battery (immediately after replacement) or just after gasoline refueling. When step 703 is NO, the smoothing ratios sma and smb are set so as to perform the smoothing calculation at the normal smoothing degree (step 704). When step 703 is YES, the fuel calculated this time The smoothing rates sma and smb are set so as to increase the learning speed by reducing the degree of smoothing for the property coefficient F3 (step 705).
[0086]
Thereafter, in step 706, from the fuel property coefficient F3 calculated this time, the learning value KL at the previous operation, and the respective annealing rates sma and smb, the following equation (3):
KN3 = (F3 × sma) + (KL × smb) (3)
Is used to calculate the third fuel property determination value KN3.
[0087]
As described above, the first to third fuel property determination values KN1, KN2, and KN3 are obtained by smoothing the fuel property coefficients F1, F2, and F3 at the predetermined smoothing rates sma and smb by the learning value KL at the previous operation. However, it is desirable that the annealing rates sma and smb are changed according to the accuracy and reliability of the fuel property coefficients F1, F2 and F3. That is, when comparing the fuel property coefficients F1, F2, and F3, the reliability of the fuel property coefficient F3 is the highest and the reliability of the fuel property coefficient F1 is the lowest. So as an example,
When calculating the first fuel property determination value KN1, in the above equation (1), sma = 0.2, smb = 0.8,
When calculating the second fuel property determination value KN2, in the above equation (2), sma = 0.3, smb = 0.7,
When calculating the third fuel property determination value KN3, in the above equation (3), sma = 0.5, smb = 0.5,
Annealing calculation is performed using the annealing rates sma and sb set respectively. As a result, the degree of smoothing of each fuel property coefficient decreases in the order of F1, F2, and F3 (the reflection rate increases), and the reliability of the fuel property determination result can be further improved.
[0088]
In the present embodiment, the process of FIG. 3 corresponds to the rotational speed control means, and the process of step 130 (FIG. 4A) corresponds to the intake air amount control means, and step 150 (FIG. 4B). This process corresponds to the ignition timing control means. 5 and 6 corresponds to the fuel property determination means, of which the processing at step 500 (FIG. 9) is the first determination means, and the processing at step 700 (FIG. 11) is the second determination means. In addition, the process of step 300 (FIG. 7) corresponds to a third determination unit.
[0089]
According to the embodiment described in detail above, the following effects can be obtained.
(A) Since the ignition timing F / B control is performed so that the engine speed Ne converges to the target speed Nt, the engine speed Ne and the intake pipe negative pressure generated at that time are stabilized, and the evaporation rate of the injected fuel is also increased. Stable without fluctuations. The fuel property can be determined with high accuracy by determining the fuel property according to the behavior of the ignition timing F / B amount ai under the state where the evaporation rate is stable.
[0090]
In particular, the maximum value aiMAX of the ignition timing F / B amount is corrected with the upper limit qiMAX of the intake F / B amount to calculate the fuel property coefficient F2 (second fuel property determination value KN2), while the ignition timing F / B Since the fuel property coefficient F3 (third fuel property determination value KN3) is calculated on the basis of the difference between the maximum value aiMAX and the minimum value aiMIN, the intake air amount caused by engine misalignment or change over time, Variations in air-fuel ratio, friction, etc. are canceled as appropriate. Therefore, the accuracy of fuel property determination is further improved.
[0091]
(B) Before the engine speed Ne is stabilized, that is, before the maximum value aiMAX of the ignition timing F / B amount is calculated, the fuel property is determined based on the deviation between the peak speed Npk and the target speed Nt. Therefore, the inconvenience that the fuel property cannot be determined in the period until the aiMAX is calculated at the beginning of engine startup is solved.
[0092]
(C) The fuel property determination value is stored in the backup RAM 34, and the stored value (learned value KL) in the backup RAM 34 is read and used until a new fuel property is determined at the next engine start. Also, the fuel properties can be determined by substituting the backup value.
[0093]
(D) The newly determined fuel property coefficients F1 to F3 are smoothed using the learned value KL stored in the backup RAM 34, and the first to third fuel property determination values KN1 to KN3 are calculated. A suitable control device can be implemented.
[0094]
(E) When it is immediately after the battery is turned on (immediately after replacement) or immediately after gasoline refueling, the degree of smoothing of the fuel property coefficients F1 to F3 calculated from time to time is reduced. The fuel property determination values KN1 to KN3 can be learned quickly to the true value, and the fuel property can be correctly determined.
[0095]
(F) Since the degree of smoothing (annealing ratios sma, smb) is changed according to the accuracy of the fuel property coefficients F1 to F3, the reliability of the fuel property determination result can be further improved.
[0096]
(G) Since the fuel property determination is prohibited when the idle state is canceled or when the state of the electric load or the like changes before and after the start of the ignition timing F / B control, the fuel property determination parameter is incorrect. And the reliability of the apparatus is improved.
[0097]
(H) As described above, highly accurate and reliable fuel property determination values (KN1 to KN3) are obtained, and the determination values are reflected in the fuel injection control, so that the controllability is improved, and as a result, the exhaust emission Improvement can be achieved.
[0098]
(Second Embodiment)
When the ignition timing F / B control is performed as in the above-described embodiment, the degree of increase in the rotational speed (degree of torque increase) differs depending on the advance amount of the ignition timing, and the influence on the fuel property determination result. Can be considered. That is, as shown in FIG. 14, as the ignition timing becomes the advance side, the inclination of the increase in the rotational speed becomes gentle, and if the fuel property is determined using the ignition timing as it is regardless of the advance angle, the determination result of the fuel property is obtained. Influenced. Therefore, in the present embodiment, the ignition timing control amount (that is, the maximum value aiMAX and the minimum value aiMIN of the ignition timing F / B amount) used for determining the fuel property is corrected according to the advance angle of the ignition timing, The fuel property is determined based on the corrected ignition timing control amount.
[0099]
FIG. 15 is a flowchart showing a procedure for calculating the maximum value of the ignition timing F / B amount, and this processing is performed in place of FIG. 8 described above. However, in FIG. 15, the same processing steps as those in FIG. 8 are given the same step numbers, and some of them are omitted. That is, in FIG. 15, in steps 401 to 404, as described in FIG. 8, the previous value avai0 and the current value avai are calculated for the average value of the ignition timing F / B amount, and “avai0 ≧ avai? And “| ΔN (= Nt−Ne) | <Nb?”. If both of them are affirmatively determined, in step 405, the previous average value avai0 of the ignition timing F / B amount is set as the maximum value aiMAX of the ignition timing F / B amount.
[0100]
Steps 421 to 423 after the calculation of aiMAX are newly added steps. In step 421, the ignition timing Aop at the time of aiMAX calculation is set to “aBASE1”. Here, the ignition timing Aop is a control command value including the ignition timing F / B amount ai, the base advance amount, and the like, and changes as shown in FIG. 17 when the engine is started. That is, when the engine speed Ne reaches a predetermined speed after starting, a predetermined advance amount is set as the ignition timing Aop. After that, when the ignition timing F / B control is started, the base advance amount and the ignition timing are set. The ignition timing Aop is controlled in the form of adding the F / B amount ai.
[0101]
In the subsequent step 422, the ignition timing correction coefficient KA is calculated according to aBASE1. In this case, the smaller the aBASE1 is, the smaller the correction coefficient KA is set.
[0102]
Thereafter, in step 423, the maximum value aiMAX of the ignition timing F / B amount calculated in step 405 is multiplied by the correction coefficient KA, and the product is newly set to aiMAX. Finally, as described above, the maximum value calculation completion flag xaiMAX is set to “1” (step 406), and this process is terminated.
[0103]
FIG. 16 is a flowchart showing a procedure for calculating the minimum value of the ignition timing F / B amount. This process is performed in place of the above-described FIG. However, in FIG. 16, the same processes as those in FIG. 10 are given the same step numbers, and some of them are omitted. That is, in FIG. 16, in steps 601 to 609, as described with reference to FIG. 10, the previous value avai0 and the current value avai are calculated for the average value of the ignition timing F / B amount, and A minimum value aiMIN of the ignition timing F / B amount is calculated.
[0104]
Steps 621 to 623 after the calculation of aiMIN are newly added steps. In step 621, the ignition timing Aop (control command value) at the time of aiMIN calculation is set to “aBASE2”. In the subsequent step 622, an ignition timing correction coefficient KA is calculated according to aBASE2. In this case, the smaller the aBASE2 is, the smaller the correction coefficient KA is set.
[0105]
Thereafter, in step 623, the minimum value aiMIN of the ignition timing F / B amount calculated in steps 607 and 609 in FIG. 10 is multiplied by the correction coefficient KA, and the product is newly set to aiMIN. Finally, as described above, the minimum value calculation completion flag xaiMIN is set to “1” (step 610), and this process is terminated.
[0106]
As described above, according to the second embodiment, the ignition timing control amount (aiMAX, aiMIN) used for determining the fuel property is corrected according to the ignition timing Aop, so that the fuel property determination with higher accuracy is performed. become able to.
[0107]
In addition to the above, the present invention can be embodied in the following forms.
In the above embodiment, when the maximum value aiMAX of the ignition timing F / B amount is calculated, when avai0 ≧ avai and | ΔN | <Nb, the engine speed Ne is stabilized with respect to the target speed Nt. The maximum value aiMAX of the ignition timing F / B amount is calculated (the process of FIG. 8), but other calculation methods may be used. For example, when the engine speed Ne is stabilized with respect to the target speed Nt, the proportional term (p term) of the ignition timing F / B amount ai becomes almost 0, and the integral term (i term) becomes the maximum value. The integral term at that time is calculated as aiMAX.
[0108]
In the above embodiment, the maximum value aiMAX of the ignition timing F / B amount is corrected with the upper limit value qiMAX of the intake F / B amount to calculate the fuel property coefficient F2 (second fuel property determination value KN2), while ignition is performed. The fuel property coefficient F3 (third fuel property determination value KN3) is calculated based on the difference between the maximum value aiMAX and the minimum value aiMIN of the timing F / B amount. Only one of these two fuel property coefficients is calculated. May be calculated.
[0109]
Even when any one of these fuel property coefficients is used, the fuel property can be determined under the condition that the evaporation rate of the fuel is stabilized, and the accuracy is improved. Also, variations in intake air amount, air-fuel ratio, friction, and the like due to engine misalignment and changes over time are canceled as appropriate. Therefore, the accuracy of fuel property determination is further improved.
[0110]
In the above embodiment, the first fuel property determination value KN1 is calculated based on the deviation ΔNpt between the peak rotational speed Npk and the target rotational speed Nt. The fuel property determination value KN1 may be calculated. Actually, in step 302 of FIG. 7, the peak rotational speed Npk is used instead of the deviation ΔNpt, and the fuel property coefficient F1 is calculated according to the peak rotational speed Npk. Then, in step 306 in the figure, the first fuel property determination value KN1 is calculated from the fuel property coefficient F1.
[0111]
In addition, it may be arbitrary whether or not to perform the above-described process of calculating the first fuel property determination value KN1 (fuel property coefficient F1). If not implemented, the learning value KL in the backup RAM 34 may be read and used until the second or third fuel property determination values KN2, KN3 (fuel property coefficients F2, F3) are calculated.
[0112]
When determining the fuel property according to the ignition timing F / B amount ai, the change rate such as the change rate (slope of change) of the ignition timing F / B amount ai and the elapsed time from the maximum value aiMAX to the minimum value aiMIN. The fuel property may be determined according to the above, or the fuel property may be determined according to the maximum value aiMAX of the ignition timing F / B amount itself. For example,
・ The larger the change rate (change slope) of ai, the heavier it is.
-The longer the elapsed time from aiMAX to aiMIN, the heavier it is.
・ The larger aiMAX is, the heavier it is.
The fuel property is determined as follows.
[0113]
Further, in the control device that converges the engine speed to the target speed by the intake F / B control, the fuel property may be determined according to the intake F / B amount. Alternatively, the fuel property may be determined according to the fuel injection F / B amount in a control device that converges the engine speed to the target rotation speed by the fuel injection F / B control. Also in these cases, since the fuel property is determined under the state where the rotational speed is stable, that is, under the state where the evaporation rate is stable, the fuel property can be accurately determined.
[0114]
In the above embodiment, the degree of smoothing of the fuel property coefficients F1 to F3 is reduced immediately after the battery is turned on (immediately after replacement) or immediately after gasoline refueling. However, even if the processing is eliminated and the configuration is simplified. good. Further, it is possible to eliminate the processing of making the fuel property coefficients F1 to F3 by the learning value KL and to use the fuel property coefficients F1 to F3 as the determination values as they are.
[0115]
In the above embodiment, the present invention is applied to the fuel injection control system and the fuel injection amount is controlled according to the fuel property level. However, the present invention may be applied to other applications. For example, the fuel property level determined as described above is applied to diagnosis processing (failure diagnosis processing). In this case, it is possible to suitably execute the diagnosis process by changing the diagnosis determination value according to the fuel property level or determining whether the diagnosis process is appropriate.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an outline of an engine fuel injection control system according to an embodiment of the invention.
FIG. 2 is a time chart showing an outline of rotation speed F / B control.
FIG. 3 is a flowchart showing a procedure of rotation speed F / B control.
FIG. 4 is a flowchart showing a procedure of intake F / B control and ignition timing F / B control.
FIG. 5 is a flowchart showing a procedure for determining a fuel property level.
FIG. 6 is a flowchart illustrating a procedure for determining a fuel property level, following FIG. 5;
FIG. 7 is a flowchart showing a procedure for calculating a first fuel property determination value.
FIG. 8 is a flowchart showing a procedure for calculating the maximum value of the ignition timing F / B amount.
FIG. 9 is a flowchart showing a procedure for calculating a second fuel property determination value.
FIG. 10 is a flowchart showing a procedure for calculating a minimum value of an ignition timing F / B amount.
FIG. 11 is a flowchart showing a procedure for calculating a third fuel property determination value;
FIG. 12 is a diagram for setting an upper limit value of an intake air amount F / B amount.
FIG. 13 is a diagram for calculating a fuel increase coefficient.
FIG. 14 is a diagram showing the relationship between the ignition timing and the degree of rotation speed increase.
FIG. 15 is a flowchart showing a procedure for calculating the maximum value of the ignition timing F / B amount in the second embodiment.
FIG. 16 is a flowchart showing a procedure for calculating the minimum value of the ignition timing F / B amount in the second embodiment.
FIG. 17 is a time chart for explaining the transition of ignition timing Aop.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Engine, 18 ... Injector, 19 ... Spark plug, 30 ... ECU, 31 ... Revolution speed control means, Fuel property determination means, Ignition timing control means, Intake amount control means, First determination means, Second determination means As a CPU, 34... Backup RAM.

Claims (13)

Rotational speed control means for performing rotational speed feedback control so that the rotational speed of the internal combustion engine converges to the target rotational speed during idling after the internal combustion engine is started,
Fuel property determining means for determining the fuel property according to the behavior of the control amount at the time of the rotational speed feedback control by the rotational speed control means;
Equipped with a,
The rotational speed control means is an ignition timing control means for feedback controlling the ignition timing so as to converge the engine rotational speed to the target rotational speed,
The fuel property determination means includes an ignition timing control amount when the engine speed is stabilized with respect to a target speed during feedback control by the ignition timing control means, and an ignition timing control amount that converges after the rotation speed is stabilized. And determining the fuel property based on the difference between the ignition timing control amounts . The rotational speed control means further comprises an intake air amount control means for feedback control of an intake air amount to the internal combustion engine so that the engine rotational speed converges to a target rotational speed at the time of idling after the internal combustion engine is started, and the ignition timing control When the intake control amount reaches the upper limit in the feedback control of the intake air amount, the means performs feedback control of the ignition timing so as to converge the engine speed to the target speed,
  The fuel property determining means includes
  The ignition timing control amount when the engine speed is stabilized with respect to the target speed during feedback control by the ignition timing control means is corrected by the upper limit value of the intake control amount during feedback control by the intake amount control means, First determination means for determining a fuel property according to the corrected ignition timing control amount;
  Fuel properties based on the difference between the ignition timing control amount when the engine speed is stabilized with respect to the target speed during feedback control by the ignition timing control means and the ignition timing control amount that converges after the rotation speed is stabilized Second determining means for determining
  The fuel property is determined by the first determination means until the engine speed is stabilized with respect to the target speed and thereafter the ignition timing control amount converges. When the ignition timing control amount converges, the second determination means 2. The control apparatus for an internal combustion engine according to claim 1, wherein the control is shifted to fuel property determination. The control apparatus for an internal combustion engine according to claim 2,
  There is further provided a third determination means for determining the fuel property based on “peak speed” at the time of engine start or “deviation between the peak speed and the target speed”, and the engine speed is controlled during feedback control by the ignition timing control means. A control device for an internal combustion engine that determines fuel properties by the third determination means before stabilization with respect to a target rotational speed. The control apparatus for an internal combustion engine according to any one of claims 1 to 3,
  A control device for an internal combustion engine that corrects an ignition timing control amount for use in determination of fuel properties in accordance with the degree of advance of the ignition timing at that time. The determined fuel property is backed up before the operation of the internal combustion engine is stopped, and the determined value of the backed up fuel property is read and used until a new fuel property is determined at the next engine start. The control apparatus for an internal combustion engine according to any one of the above. The control apparatus for an internal combustion engine according to claim 5,
  The newly determined fuel property is added to the fuel property judgment value backed up at the previous operation while smoothing at a predetermined smoothing rate, and the added value is used as the fuel property judgment value. Control device. The control apparatus for an internal combustion engine according to claim 6,
  A control apparatus for an internal combustion engine, which reduces the degree of smoothness of a newly determined fuel property at the beginning when a vehicle-mounted battery is newly connected to a memory for backing up a fuel property determination value. The control apparatus for an internal combustion engine according to claim 6,
  Immediately after refueling, control of the internal combustion engine to reduce the degree of smoothness of the newly determined fuel properties apparatus. The control apparatus for an internal combustion engine according to claim 2,
  The newly determined fuel property is smoothed by the fuel property determination value backed up during the previous operation, and the calculated value is used as the fuel property determination value. The fuel property determination value by the second determination means A control device for an internal combustion engine that reduces the degree of smoothing when compared to when determining the fuel property determination value by the first determination means. The control apparatus for an internal combustion engine according to claim 3,
  The newly determined fuel property is smoothed by the fuel property determination value backed up during the previous operation, and the calculated value is used as the fuel property determination value. The fuel property determination value by the third determination means A control device for an internal combustion engine that increases the degree of smoothing when compared to when determining the fuel property determination value by the first or second determination means. The control apparatus for an internal combustion engine according to claim 2,
  An internal combustion engine that prohibits determination of fuel properties by the first or second determination means when the idle state is released or when the state of an electric load or the like changes before and after the start of feedback control by the ignition timing control means Control device. 12. The fuel injection control system for increasing a predetermined fuel injection amount during start-up and warm-up of the internal combustion engine, and changing the degree of fuel injection amount increase according to the determined fuel property. The control apparatus for an internal combustion engine according to any one of the above. Rotational speed control means for performing rotational speed feedback control so that the rotational speed of the internal combustion engine converges to the target rotational speed during idling after the internal combustion engine is started,
  Fuel property determining means for determining the fuel property according to the behavior of the control amount at the time of the rotational speed feedback control by the rotational speed control means;
With
  The rotational speed control means includes an intake air amount control means for performing feedback control of an intake air amount to the internal combustion engine so that the engine rotational speed is converged to a target rotational speed, and an intake control amount is an upper limit value by feedback control of the intake air amount. When it reaches, the ignition timing control means that feedback controls the ignition timing so as to converge the engine speed to the target speed,
  The fuel property determining means determines an ignition timing control amount when the engine speed is stabilized with respect to a target speed during feedback control by the ignition timing control means, and an intake control amount at the time of feedback control by the intake amount control means. Is a control device for an internal combustion engine that corrects the fuel property according to the corrected ignition timing control amount.

Images