JP2008223501A - Control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent erroneous determination of a used fuel accompanying with amount-reduction/correction of the fuel injected from a fuel injection valve by feeding of an evaporated fuel. <P>SOLUTION: The control device for amount-reducing/correcting a fuel injection amount injected from the fuel injection valve according to a feeding amount of the evaporated fuel and angle-delaying/correcting an ignition timing by generation of knocking is provided with a used fuel determination means for determining whether or not the used fuel is a low octane number fuel. The used fuel determination means performs determination of the used fuel based on the angle-delaying/correction amount of the ignition timing. A determination condition is set such that it is hardly determined that the used fuel is the low octane number fuel during feeding of the evaporated fuel as compared with the case of non-feeding. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to engine control technology, and more particularly to determination of fuel used and ignition timing control technology based on the determination result.

  As a vehicle engine, an engine provided with an evaporative fuel supply device that supplies evaporative fuel in a fuel tank to the engine is known (Patent Document 1). By providing such an evaporative fuel supply device, it is possible to prevent the evaporative fuel from being released into the atmosphere, and to contribute to an improvement in fuel consumption. In an engine provided with such an evaporative fuel supply device, as a result of supplying evaporative fuel to the combustion chamber in addition to the fuel injected from the fuel injection valve, the air-fuel ratio deviates from the target value. For this reason, the deviation from the target value of the air-fuel ratio is eliminated by correcting the amount of fuel injected from the fuel injection valve to be reduced.

  On the other hand, high-octane fuel (high-octane gasoline) with high knock resistance and low-octane fuel (regular gasoline) with low knock resistance are known as engine fuels. Here, even if the vehicle is designated to use high-octane fuel, low-octane fuel may actually be used. In vehicles in which the use of high-octane fuel is specified, the ignition timing is defined on the premise that high-octane fuel is used. Therefore, if low-octane fuel is used, engine knocking is likely to occur. Thus, a technique has been proposed in which the type of fuel used is determined and the ignition timing is switched according to the type of fuel used (Patent Document 2).

JP 7-317582 A Japanese Patent Publication No. 4-75396

  By the way, the fuel injected from the fuel injection valve has an effect of cooling the intake air by its latent heat of vaporization. In particular, as in the case of in-cylinder injection (direct injection), when fuel is injected in a high-temperature atmosphere, the vaporization is promoted, so that the intake air cooling effect due to vaporization latent heat is high. When the intake air is cooled, there is an advantage that knocking hardly occurs.

  However, since the evaporated fuel has already vaporized, the cooling effect of the intake air due to the latent heat of vaporization cannot be expected. Therefore, if the fuel injected from the fuel injection valve is corrected to decrease in accordance with the supply of the evaporated fuel, the cooling effect of the intake air by the latent heat of vaporization is lost accordingly, and knocking is likely to occur.

  For this reason, in an engine equipped with an evaporative fuel supply device, when the type of fuel used is determined and the ignition timing is switched according to the type of fuel used, the cause of knocking is the correction of the fuel decrease accompanying the supply of evaporative fuel. In some cases, it may be erroneously determined to be caused by the type of fuel used, although it is caused by this. If it is erroneously determined that a low-octane fuel is being used while using a high-octane fuel, the ignition timing of the fuel is switched to the ignition timing for a low-octane fuel, which is normally demonstrated by the use of a high-octane fuel. Performance may not be achieved.

  Therefore, an object of the present invention is to prevent erroneous determination of the fuel used, which is caused by correcting the amount of fuel injected from the fuel injection valve to be reduced by supplying evaporated fuel.

  According to the present invention, in an engine control device provided with an evaporative fuel supply device for supplying evaporative fuel in a fuel tank to an engine, fuel injected from a fuel injection valve of the engine according to an operating state of the engine A fuel injection amount setting means for setting an injection amount; a reduction correction means for correcting a decrease in the fuel injection amount of the engine in accordance with the supply amount of the evaporated fuel; and an engine in accordance with the operating state of the engine. Ignition timing setting means for setting the ignition timing of the spark plug, knocking determination means for determining whether or not knocking has occurred in the engine, and when the knocking determination means determines that knocking has occurred , Delay angle correcting means for correcting the ignition timing set by the ignition timing setting means, and determining whether or not the fuel used is a low octane fuel The ignition timing setting means is configured to replace the ignition timing for high octane fuel when the fuel used is determined to be low octane fuel by the fuel determining means. The ignition timing for the octane fuel is set, and the fuel use determining means determines the fuel used based on the retardation correction amount by the retardation correction means, and the supply of the evaporated fuel is more than the case of non-supply. In addition, a control device is provided in which a determination condition is set so that it is difficult to determine that the fuel used is the low-octane fuel.

  According to the control device of the present invention, the determination condition is set so that it is difficult to determine that the used fuel is the low-octane fuel during the supply of the evaporated fuel than in the case of non-supply. For this reason, when the knocking occurs due to the reduction correction of the fuel injected from the fuel injection valve by the supply of the evaporated fuel, and the retardation correction is performed, the used fuel is erroneously changed to the low octane number. The case where it is determined as fuel can be reduced, and erroneous determination of the fuel used can be prevented.

  In the present invention, the used fuel determination means determines that the used fuel is the low-octane fuel when the retardation correction amount reaches a predetermined threshold, and the threshold during the supply of the evaporated fuel is determined. May be configured to be set large. By setting the threshold value large during the supply of the evaporated fuel, it is possible to reduce the case where the used fuel is erroneously determined as the low octane number fuel, and to prevent erroneous determination of the used fuel.

  Further, in the present invention, the used fuel determining means determines that the used fuel is the low octane fuel when the retardation correction amount reaches a predetermined threshold value, and during the supply of the evaporated fuel, Even if the retardation correction amount reaches the threshold value, the fuel used may be determined not to be the low octane fuel. Even when the retardation correction amount reaches the threshold during the supply of the evaporated fuel, it is determined that the used fuel is the high octane fuel, so that the used fuel is erroneously the low octane fuel. Can be reduced, and erroneous determination of the fuel used can be prevented.

  In the present invention, it further comprises calculation means for calculating an index value indicating a ratio of the supply amount of the evaporated fuel to the fuel injection amount set by the fuel injection amount setting means. May be set when the index value satisfies a predetermined condition. According to this structure, the determination accuracy of the used fuel can be improved.

  In the present invention, the fuel consumption determining unit further includes a calculation unit that calculates an index value indicating a ratio of the supply amount of the evaporated fuel to the fuel injection amount set by the fuel injection amount setting unit. When the evaporated fuel is being supplied and the index value satisfies a predetermined condition, even if the retardation correction amount reaches the threshold value, the used fuel is low. It may be determined that the fuel is not an octane fuel. According to this structure, the determination accuracy of the used fuel can be improved.

  In addition, the present invention is suitable for a case where the engine is arranged such that the fuel injection valve directly injects fuel into a combustion chamber of the engine. In the case of in-cylinder injection, since the cooling effect of intake air by latent heat of vaporization is high, the influence of a decrease in the cooling effect of intake air by the supply of evaporated fuel is large. According to the present invention, the fuel injection valve is supplied by the supply of evaporated fuel. When the knocking occurs due to the reduction correction of the fuel injected from the engine and the retardation correction is performed, the case where the used fuel is erroneously determined to be the low octane fuel can be reduced. It is possible to prevent erroneous determination of the fuel used.

  Further, the present invention is suitable when the engine is arranged such that the fuel injection valve injects fuel toward the back surface of the intake valve of the engine. Since the intake valve becomes high temperature, when fuel is injected to the back surface thereof, the vaporization of the fuel is promoted, and the cooling effect of the intake air by the latent heat of vaporization is enhanced. Therefore, the influence of the decrease in the intake air cooling effect due to the supply of the evaporated fuel is large. According to the present invention, knocking occurs due to the reduction correction of the fuel injected from the fuel injection valve by the supply of the evaporated fuel. In addition, when the retardation correction is performed, it is possible to reduce the case where the used fuel is erroneously determined as the low octane fuel, and to prevent erroneous determination of the used fuel.

  As described above, according to the present invention, it is possible to prevent erroneous determination of the fuel to be used accompanying the reduction correction of the fuel injected from the fuel injection valve by supplying the evaporated fuel.

<First Embodiment>
FIG. 1 is a control system diagram of an engine 1 to which a control device A according to an embodiment of the present invention is applied. In the following description, the terms “upstream” and “downstream” of the passage follow the direction of the flow of fluid flowing through the passage.

  In this embodiment, the engine 1 is an in-line multi-cylinder reciprocating engine, and includes a cylinder block 2, a cylinder head 3, and a crankcase 4. In the case of the present embodiment, the engine 1 is a naturally aspirated engine, but the present invention is also applicable to control of an engine with a supercharger.

  A cylinder 22 on which the piston 21 slides is formed in the cylinder block 2, and the reciprocating motion of the piston 21 is converted into the rotational motion of the crankshaft 41. A combustion chamber 31 is formed between the cylinder block 2 and the cylinder head 3. A water jacket through which cooling water passes is provided in the cylinder block 2, and a water temperature sensor 201 for detecting the temperature of the cooling water passing through the water jacket is provided in the cylinder block 2. The cylinder block 2 is provided with a knock sensor 202 that detects the occurrence of knocking.

  The cylinder head 3 includes an intake port 32 and an exhaust port 33 communicating with the combustion chamber 31. The intake port 32 is opened and closed by an intake valve 34, and the exhaust port 33 is opened and closed by an exhaust valve 35. The cylinder head 3 is provided with a spark plug 36 facing the tip electrode in the combustion chamber 31, and ignites a mixture of air and fuel supplied into the combustion chamber 31. The cylinder head 3 is also provided with an electronically controlled fuel injection valve 37. In the case of this embodiment, the fuel injection valve 37 is disposed so as to inject fuel directly into the combustion chamber 31 (in-cylinder injection). By injecting the fuel into the cylinder, the vaporization of the fuel is promoted and the intake air is cooled by latent heat of vaporization. Cooling the intake air is effective in suppressing the occurrence of knocking in the engine 1.

  In this embodiment, the fuel is injected into the cylinder in this way, but it may be port injection. In this case, it is desirable that the fuel injection valve 37 ′ shown by a broken line in FIG. 1 is arranged so as to inject fuel toward the back surface of the intake valve 34. Since the intake valve 34 is at a high temperature, the fuel injection direction of the fuel injection valve 37 ′ is directed to the back surface of the intake valve 34, so that fuel vaporization is promoted and the intake air is cooled by latent heat of vaporization.

  The engine 1 includes a high-pressure pump 5 that pumps fuel to the fuel injection valve 37. The high-pressure pump 5 is provided in the cylinder head 3 and is driven by a camshaft that drives the intake valve 34 or the exhaust valve 35. The camshaft rotates by obtaining a driving force from the crankshaft 41. The high-pressure pump 5 pressure-feeds the fuel pumped through the low-pressure pump 81 and the regulator 82 in the fuel tank 8 to the fuel injection valve 37.

The crankcase 4 is provided with a crank angle sensor 401 that detects the rotation angle of the crankshaft 41. An intake passage 6 communicates with the intake port 32. An air filter 61, an air flow meter (intake air amount sensor) 601, an electronically controlled throttle valve 62, and a surge tank 63 are disposed in the intake passage 6 from the upstream side. The throttle valve 62 detects the driver's operation amount with respect to the accelerator pedal 10 by the accelerator pedal sensor 11, and the opening degree is controlled according to the operation amount. An exhaust passage 7 communicates with the exhaust port 33. An air-fuel ratio sensor (O ₂ sensor) 701 and catalytic converters 71 and 72 are provided in the exhaust passage 7 from the upstream side.

  The engine 1 is provided with an evaporated fuel supply device 9 for supplying the evaporated fuel in the fuel tank 8 to the engine 1. The evaporative fuel supply device 9 includes a canister 92 into which evaporative fuel is sent via an evaporative fuel passage 91 connected to the fuel tank 8, and a purge valve provided in the middle of a purge passage 94 that connects the canister 92 and the surge tank 63. 93.

  The canister 92 contains, for example, activated carbon, and adsorbs and captures evaporated fuel. The purge valve 93 supplies the evaporated fuel adsorbed and captured by the canister 92 to the intake passage 6 (here, the surge tank 63). The purge valve 93 is an electronically controlled control valve that is controlled by the control device A and can adjust the flow rate, and is controlled to open and close in accordance with the operating state of the engine 1.

  FIG. 3A is a diagram illustrating an example of an operation region in which the evaporated fuel is supplied to the intake passage 6. In the example of the figure, the evaporated fuel supply region (purge region) is set except when the load and rotation speed of the engine 1 are high load or high rotation speed. When the operating state of the engine 1 belongs to the evaporated fuel supply region, the purge valve 93 is opened to supply the evaporated fuel to the engine 1, and when not belonging, the purge valve 93 is closed to stop the supply of the evaporated fuel.

  In addition, as a load of the engine 1, it can be set as the intake charge rate based on the detection result of the air flow meter 601, for example. In the example shown in the figure, in the fuel vapor supply region, the supply amount is small (10% of the total fuel supply amount to the combustion chamber 31) in the region where the load and the rotational speed of the engine 1 are relatively high or high. %, And in a relatively low load or low rotational speed region, the supply amount is large (25 to 45% of the total supply amount of fuel to the combustion chamber 31. The supply amount of evaporated fuel is the opening and closing of the purge valve 93. Controlled by control.

  The control device A includes a CPU 101, a ROM 102, a RAM 103, and an I / F (interface) 104. The CPU 101 controls the engine 1 by executing a control program stored in the ROM 102. In addition to the program executed by the CPU 101, the ROM 102 stores information in which ignition timing, fuel injection timing, fuel injection amount, and the like are set according to the operating state of the engine 1. The ignition timing includes basic ignition timing data for a high octane number and basic ignition timing data for a low octane number. The basic ignition timing for the high octane number is set, for example, by advancing the ignition timing relative to the basic ignition timing for the low octane number. The RAM 103 stores temporary data. The ROM 102 and RAM 103 may be other storage means.

  Detection results of the water temperature sensor 201, the knock sensor 202, the crank angle sensor 401, the air flow meter 601, the air-fuel ratio sensor 701, and the accelerator pedal sensor 11 are input to the I / F 104, and the CPU 101 can read them. A control command from the CPU 101 is output to the spark plug 36, the fuel injection valve 37, the throttle valve 62, and the purge valve 93 via the I / F 104.

  FIG. 2 is a flowchart illustrating an example of processing executed by the CPU 101 of the control device A. The example in the figure shows processing related to ignition by the spark plug 36 and fuel injection by the fuel injection valve 37.

  In S1, it is determined whether or not an initialization condition is satisfied. The initialization condition is, for example, when the engine 1 is started (when the ignition is on). If yes, go to S2, otherwise go to S3. In S2, the fuel used is set to a high octane fuel. That is, the engine 1 is premised on the use of high-octane fuel, and the process proceeds on the assumption that the high-octane fuel is once used for control regardless of the type of fuel actually used.

  In S3, the detection result of each sensor is acquired. In S4, the fuel injection amount injected from the fuel injection valve 37 is first set as the basic fuel injection amount. The basic fuel injection amount includes the load (intake filling rate based on the detection result of the air flow meter 601), the engine speed based on the detection result of the crank angle sensor 401, the engine temperature based on the detection result of the water temperature sensor 201, and the air-fuel ratio sensor 701 Information stored in the ROM 102 is read and set based on the operating state of the engine 1 such as the air-fuel ratio based on the detection result.

  In S5, the supply amount of the evaporated fuel supplied into the combustion chamber 31 is calculated. The supply amount of the evaporated fuel is estimated based on the detection result of the air-fuel ratio sensor 701, for example. In S6, the amount of fuel injected from the fuel injection valve 37 set in S4 is corrected. Here, the injection amount is corrected to decrease in accordance with the supply amount of the evaporated fuel calculated in S5. When the corrected injection amount is the final injection amount, (final injection amount) = (basic fuel injection amount set in S4) − (evaporated fuel supply amount calculated in S5).

  In S7, the basic ignition timing of the spark plug 36 is set. The basic ignition timing includes the load (intake filling rate based on the detection result of the air flow meter 601), the engine speed based on the detection result of the crank angle sensor 401, the engine temperature based on the detection result of the water temperature sensor 201, and the detection of the air-fuel ratio sensor 701. Information stored in the ROM 102 is read and set according to the operating state of the engine 1 such as the air-fuel ratio based on the result. If the fuel used is set to a high octane fuel, the basic ignition timing data for the high octane fuel is read and set, and the fuel used is a low octane fuel in the fuel use determination process (S11) described later. If the basic ignition timing for high octane number is set, the basic ignition timing data for low octane number is read and set instead of the basic ignition timing data for high octane number.

  In S8, the fuel injection timing from the fuel injection valve 37 is set. The injection timing includes the load (intake filling rate based on the detection result of the air flow meter 601), the engine speed based on the detection result of the crank angle sensor 401, the engine temperature based on the detection result of the water temperature sensor 201, and the detection result of the air-fuel ratio sensor 701. The information stored in the ROM 102 is read and set according to the operating state of the engine 1 such as the air-fuel ratio based on the above.

  In S9, it is determined whether knocking has occurred in the engine 1 based on the detection result of the knock sensor 202 acquired in S1. If knocking has occurred, the process proceeds to S10, and if not, the process proceeds to S11. In S10, the ignition timing correction amount is updated. Here, the correction amount of the ignition timing set in the previous process is retarded. In S11, the ignition timing correction amount is updated. Here, the ignition timing correction amount set in the previous process is advanced. Note that a limit value is determined in advance for the correction amount of the ignition timing, and the correction amount is updated within a range of correction amount = 0 to the retard side limit value.

  In S12, a used fuel determination process is performed in which it is determined whether the currently used fuel is a low-octane fuel based on the ignition timing correction amount (retard angle correction amount) updated in S10. The determination result is reflected in the basic ignition timing setting process of S7 in the subsequent processes. Details of the used fuel determination process will be described later.

  In S13, the basic ignition timing set in S7 is corrected based on the correction amount updated in S10 or S11, and the final ignition timing is set. In S14, when the arrival of the injection timing set in S8 is detected by the crank angle sensor 401, the fuel injection valve 37 injects the final injection amount set in S6. In S15, when the arrival of the final ignition timing set in S13 is detected by the crank angle sensor 401, the air-fuel mixture in the combustion chamber 31 is ignited by the spark plug 36. Thus, one unit of processing is completed.

  Next, the used fuel determination process in S12 will be described with reference to FIG. FIG. 4 is a flowchart showing the used fuel determination process. In S21, it is determined whether or not the operation state of the engine 1 belongs to a predetermined operation region (fuel determination region). If applicable, the process proceeds to S22, and if not, the process proceeds to S26.

  In the fuel determination region, in order to improve the determination accuracy of the fuel used, it is expected that the operating state of the engine 1 is relatively stable, the detection error of the knock sensor 202 is small, and the cause of knocking is caused by the supply of evaporated fuel. Is set to the operating range. FIG. 3B is a diagram illustrating an example of the fuel determination region. The fuel determination region can be set, for example, in the range of the engine 1 having a rotational speed of 575 to 5750 rpm and the load being an intake charge rate of 0.5 to 1.0. Further, it may be a requirement that the water temperature of the engine 1 is 70 degrees Celsius or higher.

  In S22, it is determined whether or not evaporative fuel is being supplied. Whether or not the evaporated fuel is being supplied is determined, for example, based on whether or not the operating state of the engine 1 belongs to the evaporated fuel supply region shown in FIG. If yes, go to S23, otherwise go to S26.

  In S23, an index value indicating the ratio of the fuel supply amount to the basic fuel injection amount set in S2 is calculated. Here, the index value is (evaporated fuel supply amount calculated in S5) / (basic fuel injection amount set in S4) × 100 (%). However, since the index value only needs to indicate the ratio of the supply amount of the evaporated fuel, it may be, for example, (final injection amount set in S6) / (basic fuel injection amount set in S4).

  In S24, it is determined whether or not the index value calculated in S23 satisfies a predetermined condition. If applicable, the process proceeds to S25, and if not, the process proceeds to S26. In the case of the present embodiment, the condition is that the ratio of the supply amount of evaporated fuel to the basic fuel injection amount set in S4 exceeds a predetermined threshold, and the index value ((the supply amount of evaporated fuel calculated in S5)) / (Basic fuel injection amount set in S4) × 100 (%))> threshold β. The threshold value β can be determined by experimentally determining the supply amount of evaporated fuel that particularly affects the occurrence of knocking, and is, for example, about 30%.

  In S25, a threshold value α for determining the type of fuel used is set to α1. In S26, the threshold value α is set to α0. α0 and α1 are predetermined, and the relationship between them is α1> α0. For example, α0 can be set to about 70% of the limit value of the ignition timing retardation correction amount, and α1 can be set to, for example, about 90% of the limit value of the ignition timing retardation correction amount. Α1 may be set according to the index value (the larger the index value, the larger).

  In S27, based on the ignition timing correction amount (retard angle correction amount) in S10, it is determined whether or not the fuel used is a low-octane fuel. The determination is made based on whether or not the retardation correction amount has reached the threshold value α set in S25 or S26. In the case of the present embodiment, when the retardation correction amount> the threshold value α, the process proceeds to S28, where it is determined and set that the used fuel is a low octane fuel. If the retardation correction amount is not greater than the threshold value α, the setting of the fuel used is maintained. Thus, the unit fuel consumption determination process is completed.

  As described above, in the present embodiment, the determination condition is set so that it is difficult to determine that the used fuel is the low-octane fuel during the supply of the evaporated fuel as compared with the non-supply state (S22, S25). For this reason, when knocking occurs due to the reduction correction of the fuel injected from the fuel injection valve by the supply of evaporated fuel, and the delay angle correction is made, the fuel used is erroneously determined as the low octane fuel It is possible to reduce the number of cases where fuel is used, and to prevent erroneous determination of the fuel used.

  In particular, in this embodiment, when setting the determination condition so that it is difficult to determine that the used fuel is a low-octane fuel, the threshold value α is set large during the supply of the evaporated fuel (S25: α ← α1), The case where the used fuel is erroneously determined as the low octane fuel can be reduced, and the erroneous determination of the used fuel can be prevented.

  The requirement for setting the threshold value α large may be only that the fuel vapor is being supplied, but in the present embodiment, it is further required that the index value calculated in S23 satisfies a predetermined condition. (S24). This makes it difficult for the low-octane fuel to be determined as the used fuel when there is a high probability that the cause of knocking is a reduction in the cooling effect of the intake air due to the supply of evaporated fuel. Can be improved.

  Further, as in this embodiment, in the case of in-cylinder injection, since the intake air cooling effect due to vaporization latent heat is high, the basic ignition timing and the injection timing described above are premised on the suppression of the occurrence of knocking due to such a cooling effect. The control contents of the engine 1 are set. Therefore, the influence of the decrease in the cooling effect of the intake air due to the supply of the evaporated fuel is large. According to the present embodiment, the knocking is caused by correcting the decrease in the fuel injected from the fuel injection valve 37 by the supply of the evaporated fuel. When the ignition timing is retarded and the fuel used is erroneously determined as the low-octane fuel, it is possible to prevent erroneous determination of the fuel used.

Second Embodiment
In the first embodiment, when setting the determination condition so that it is difficult to determine that the used fuel is a low-octane fuel, the threshold value α is set large during the supply of the evaporated fuel, but the threshold value α is not changed. A method can also be adopted. FIG. 5 is a flowchart showing another example of the used fuel determination process in S12.

  In S31, it is determined whether or not the ignition timing correction amount (retard angle correction amount) updated in S10 has reached a preset threshold value α. The threshold α corresponds to α0 described above, and is set in advance to, for example, about 70% of the limit value of the retard correction amount of the ignition timing. If retard correction amount> threshold value α, the process proceeds to S32; otherwise, the unit fuel use determination process ends (the fuel setting is maintained).

  In S32, it is determined whether or not the operation state of the engine 1 belongs to a predetermined operation region (fuel determination region). If applicable, the process proceeds to S33, and if not applicable, the unit fuel consumption determination process is terminated (setting of fuel used is maintained). The fuel determination region is the same as the fuel determination region described in the processing of S21 in FIG. 4, and is for improving the determination accuracy of the fuel used.

  In S33, it is determined whether or not evaporative fuel is being supplied. Whether or not evaporative fuel is being supplied is determined, for example, by whether or not the operating state of the engine 1 belongs to the evaporative fuel supply region shown in FIG. 3A, as in the process of S22 of FIG. To do. If applicable, the process proceeds to S34, and if not, the process proceeds to S36. In S36, it is determined and set that the used fuel is a low-octane fuel, and the unit-used fuel determination process is completed.

  In S34, an index value indicating the ratio of the fuel supply amount to the basic fuel injection amount set in S4 is calculated. This is the same processing as S23 in FIG. In S35, it is determined whether or not the index value calculated in S34 satisfies a predetermined condition. In the case of the present embodiment, the condition is that the ratio of the supply amount of evaporated fuel to the basic fuel injection amount set in S4 exceeds a predetermined threshold, and the index value ((the supply amount of evaporated fuel calculated in S5)) / (Basic fuel injection amount set in S4) × 100 (%))> threshold β. The threshold value β can be determined by experimentally determining the supply amount of evaporated fuel that particularly affects the occurrence of knocking, and is, for example, about 30%.

  If applicable, the unit fuel consumption determination process ends (the fuel setting is maintained). If not, the process proceeds to S36, where it is determined and set that the used fuel is a low-octane fuel, and one unit of used fuel determination process is completed.

  As described above, in this embodiment, the determination condition is set so that the low-octane fuel is less likely to be determined as the used fuel during the supply of the evaporated fuel than in the non-supply (S33, S35). For this reason, when knocking occurs due to the reduction correction of the fuel injected from the fuel injection valve by the supply of evaporated fuel, and the delay angle correction is made, the fuel used is erroneously determined as the low octane fuel It is possible to reduce the number of cases where fuel is used, and to prevent erroneous determination of the fuel used.

  In particular, in the present embodiment, when setting the determination condition so that the low octane fuel is not easily determined as the use fuel, even when the retardation correction amount reaches the threshold value α during the supply of the evaporated fuel, the use fuel Is configured so that it can be determined that the fuel is not a low-octane fuel (S33, S35), it is possible to reduce the case where the fuel used is erroneously determined to be a low-octane fuel, and to prevent erroneous determination of the fuel used. be able to.

  Further, even when the retardation correction amount reaches the threshold value α during the supply of the evaporated fuel, it may be determined that the fuel used is not a low octane fuel, but in this embodiment, When the index value calculated in S34 satisfies a predetermined condition, it is determined that the fuel is not a low octane fuel (S35). This makes it difficult for the low-octane fuel to be determined as the used fuel when there is a high probability that the cause of knocking is a reduction in the cooling effect of the intake air due to the supply of evaporated fuel. Can be improved.

It is a control system figure of engine 1 to which control device A concerning one embodiment of the present invention is applied. It is a flowchart which shows the example of the process which CPU101 of the control apparatus A performs. (A) is a figure which shows the example of the operation area | region which supplies evaporative fuel to the intake passage 6, (b) is a figure which shows the example of a fuel determination area | region. It is a flowchart which shows the use fuel determination process. It is a flowchart which shows the other example of a use fuel determination process.

Explanation of symbols

A Control device 1 Engine 8 Fuel tank 9 Evaporated fuel supply device 31 Combustion chamber 34 Intake valve 36 Spark plugs 37, 37 'Fuel injection valve

Claims (7)

In an engine control device provided with an evaporative fuel supply device for supplying evaporative fuel in a fuel tank to an engine,
A fuel injection amount setting means for setting a fuel injection amount to be injected from a fuel injection valve of the engine according to an operating state of the engine;
A reduction correction means for correcting the fuel injection amount of the engine according to a supply amount of the evaporated fuel;
Ignition timing setting means for setting the ignition timing of the ignition plug of the engine according to the operating state of the engine;
Knocking determination means for determining whether knocking has occurred in the engine;
A retard correction means for retarding the ignition timing set by the ignition timing setting means when it is determined by the knock determination means that knocking has occurred;
Use fuel determination means for determining whether the use fuel is a low octane fuel,
With
The ignition timing setting means includes
If it is determined by the use fuel determination means that the fuel used is a low octane fuel, an ignition timing for the low octane fuel is set instead of the ignition timing for the high octane fuel,
The used fuel determination means includes
The use fuel is determined based on the retardation correction amount by the retardation correction means, and it is difficult to determine that the use fuel is the low-octane fuel during the supply of the evaporated fuel than when the fuel is not supplied. A control device characterized in that a determination condition is set in The used fuel determination means includes
When the retardation correction amount reaches a predetermined threshold, it is determined that the fuel used is the low octane fuel,
The control device according to claim 1, wherein the threshold is set to be large during the supply of the evaporated fuel. The used fuel determination means includes
When the retardation correction amount reaches a predetermined threshold, it is determined that the fuel used is the low octane fuel,
2. The control according to claim 1, wherein during the supply of the evaporative fuel, it is determined that the used fuel is not the low-octane fuel even when the retardation correction amount reaches the threshold value. apparatus. Furthermore,
Calculating means for calculating an index value indicating a ratio of the supply amount of the evaporated fuel to the fuel injection amount set by the fuel injection amount setting means;
The control device according to claim 2, wherein the threshold value is set to be large when the fuel vapor is being supplied and the index value satisfies a predetermined condition. Furthermore,
Calculating means for calculating an index value indicating a ratio of the supply amount of the evaporated fuel to the fuel injection amount set by the fuel injection amount setting means;
The used fuel determination means includes
When the evaporated fuel is being supplied and the index value satisfies a predetermined condition, even if the retardation correction amount reaches the threshold value, the used fuel is low. The control device according to claim 3, wherein it is determined that the fuel is not an octane fuel.   The control device according to claim 1, wherein the engine is arranged such that the fuel injection valve directly injects fuel into a combustion chamber of the engine.   The control device according to claim 1, wherein the engine is arranged such that the fuel injection valve injects fuel toward a back surface of an intake valve of the engine.

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