JP2008223502A - Control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress generation of knocking which accompanies the amount-reduction/correction of a fuel injected from a fuel injection valve by feeding an evaporated fuel. <P>SOLUTION: The control device for the engine in which an evaporated fuel feeding device for feeding the evaporated fuel in the fuel tank to the engine through a control valve is provided is provided with a setting means for setting a fuel injection amount injected from the fuel injection valve of the engine according to the operation state of the engine; a correction means for amount-reducing/correcting the fuel injection amount of the engine according to a feeding amount of the evaporated fuel; a knocking determination means for determining whether or not knocking is generated on the engine; and a control valve control means for controlling the control valve such that the feeding amount of the evaporated fuel is amount-reduced when it is determined that knocking is generated by the determination means. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to engine control technology, and more particularly to engine knocking prevention technology.

  As an engine for a vehicle, an engine provided with an evaporative fuel supply device that supplies evaporative fuel in a fuel tank to the engine is known (Patent Documents 1 and 2). 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.

JP 7-317582 A JP 2006-183554 A

  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.

  Accordingly, an object of the present invention is to suppress the occurrence of knocking that accompanies a correction for reducing the amount of fuel injected from a fuel injection valve by supplying evaporated fuel.

  According to the present invention, in the engine control device provided with the evaporated fuel supply device that supplies the evaporated fuel in the fuel tank to the engine via the control valve, the fuel injection of the engine is performed according to the operating state of the engine. A setting means for setting the fuel injection amount to be injected from the valve; a correction means for reducing the fuel injection amount of the engine in accordance with the supply amount of the evaporated fuel; and whether or not knocking has occurred in the engine And a control valve control means for controlling the control valve so that the supply amount of the evaporated fuel is reduced when it is determined by the knock determination means that knocking has occurred. There is provided a control device characterized by comprising the above.

  In the control device of the present invention, when the knocking determination means determines that knocking has occurred, the supply amount of the evaporated fuel is decreased. As a result, when knocking occurs, the correction amount for reducing the amount of fuel injected from the fuel injection valve by the correction means is reduced, and the effect of cooling the intake air due to the latent heat of vaporization of the fuel is improved. Therefore, it is possible to suppress the occurrence of knocking associated with the reduction correction of the fuel injected from the fuel injection valve by the supply of the evaporated fuel.

  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 setting means, and the control valve control means includes the knock determination means. The control valve may be controlled so that the supply amount of the evaporated fuel is reduced when it is determined that knocking has occurred and the index value satisfies a predetermined condition.

  According to this configuration, the supply amount of the evaporated fuel is reduced only when the cause of the knocking is caused by the supply of the evaporated fuel, and the supply amount of the evaporated fuel can be prevented from being reduced unnecessarily.

  Further, in the present invention, the control valve control means determines that knocking has occurred by the knocking determination means, and the operation state of the engine is a predetermined operation range in which knocking is likely to occur. The control valve may be controlled so that the supply amount of the evaporated fuel is reduced when belonging to a region.

  According to this configuration, the supply amount of the evaporated fuel is reduced only when the cause of the knocking is caused by the supply of the evaporated fuel, and the supply amount of the evaporated fuel can be prevented from being reduced unnecessarily.

  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 intake air cooling effect due to vaporization latent heat is high, the influence of the reduction of the intake air cooling effect due to the supply of evaporated fuel is large. According to the present invention, the intake air cooling effect is reduced. The occurrence of knocking can be suppressed.

  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, where the influence of a decrease in the cooling effect of the intake air due to the supply of the evaporated fuel is large, according to the present invention, the occurrence of knocking associated with the decrease in the cooling effect of the intake air can be suppressed.

  As described above, according to the present invention, it is possible to suppress the occurrence of knocking associated with the reduction correction of the fuel injected from the fuel injection valve by supplying the evaporated fuel.

  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 controls the flow rate of the evaporated fuel according to the operating state of the engine 1. Examples of the flow rate control method include control of the valve opening degree or duty control of the valve opening time.

  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 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 shown in the figure shows processing related to ignition by the spark plug 36, fuel injection by the fuel injection valve 37, and flow control of the purge valve 93.

  In S1, the detection result of each sensor is acquired. In S2, a basic control amount of the flow rate of the evaporated fuel supplied from the purge valve 93 is set. The basic control amount is set according to 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.

  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. In a relatively low load or low rotation speed region, the supply amount is large (25 to 45% of the total fuel supply amount to the combustion chamber 31).

  In S3, the injection amount of fuel injected from the fuel injection valve 37 is first set as a 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 S4, 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 S5, the amount of fuel injected from the fuel injection valve 37 set in S3 is corrected. Here, the injection amount is corrected to decrease in accordance with the supply amount of the evaporated fuel calculated in S4. When the corrected injection amount is the final injection amount, (final injection amount) = (basic fuel injection amount set in S3) − (evaporated fuel supply amount calculated in S4).

  In S6, the basic ignition timing of the spark plug 36 is set, and in S7, the fuel injection timing from the fuel injection valve 37 is set. The basic ignition timing and the injection timing are respectively 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, 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 of the fuel ratio sensor 701.

  In S8, 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 S9, and if not, the process proceeds to S19. In S9, the ignition timing correction amount is updated. Here, the correction amount of the ignition timing set in the previous process is retarded. It should be noted that limit values for the ignition timing correction amount are determined in advance on the advance side and the retard side, respectively, and the correction amount is updated within the range of the limit value. In S10, the basic ignition timing set in S6 is corrected based on the correction amount updated in S9, and the final ignition timing is set.

  In S19, the ignition timing correction amount is updated. Here, the ignition timing correction amount set in the previous process is advanced. In S20, the basic ignition timing set in S6 is corrected based on the correction amount updated in S19, and the final ignition timing is set.

  In S11 to S15, processing related to correction of the basic control amount of the purge valve 93 set in S2 is performed. First, in S11, it is determined whether or not the ignition timing correction amount updated in S9, that is, the retard correction amount has exceeded a predetermined threshold value α. If applicable, the process proceeds to S12, and if not, the process proceeds to S16. The threshold value α can be set to about 80% of the limit value of the retardation correction amount, for example. Such a determination is made to correct the basic control amount of the purge valve 93 only when the cause of knocking is due to the supply of the evaporated fuel.

  In S12, it is determined whether or not the operation state of the engine 1 belongs to a predetermined operation region (knock operation region). If yes, go to S13, otherwise go to S16. The knock operation region means an operation region of the engine 1 in which knocking is likely to occur due to the supply of the evaporated fuel, and is set in advance by an experiment or the like. FIG. 3A shows a setting example of the knock operation region, in which the engine 1 is set in an operation region with a relatively low load and a low rotational speed. This determination is performed because the basic control amount of the purge valve 93 is corrected only when the cause of knocking is caused by the supply of the evaporated fuel.

  In S13, an index value indicating the ratio of the fuel supply amount to the basic fuel injection amount set in S3 is calculated. Here, the index value is (evaporated fuel supply amount calculated in S4) / (basic fuel injection amount set in S3) × 100 (%). However, the index value only needs to indicate the ratio of the supply amount of the evaporated fuel, and may be, for example, (final injection amount set in S5) / (basic fuel injection amount set in S3).

  In S14, it is determined whether or not the index value calculated in S13 satisfies a predetermined condition. If applicable, the process proceeds to S15, and if not, the process proceeds to S16. In the case of the present embodiment, the condition is that the ratio of the supply amount of the evaporated fuel to the basic fuel injection amount set in S3 exceeds a predetermined threshold, and the index value ((the supply amount of evaporated fuel calculated in S4)) / (Basic fuel injection amount set in S3) × 100 (%))> threshold value 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%. This determination is performed because the basic control amount of the purge valve 93 is corrected only when the cause of knocking is caused by the supply of the evaporated fuel.

  In S15, the basic control amount of the purge valve 93 set in S2 is corrected so that the supply amount of the evaporated fuel is reduced. Various calculation methods can be adopted for the reduction correction amount. For example, as shown in FIG. 3B, it can be determined that the reduction correction amount increases as the index value set in S13 increases. .

  In S16, the purge valve 93 is controlled based on the basic control amount set in S2 or the control amount after the decrease correction in S15. When the control amount of the purge valve 93 is corrected to decrease in S15, the evaporated fuel supplied into the combustion chamber 31 is decreased. For this reason, in the process of FIG. 2 after the next time, the final fuel injection amount set in S5 is increased, and the occurrence of knocking is suppressed by improving the cooling effect of the intake air due to the latent heat of vaporization.

  In S17, when the arrival of the injection timing set in S7 is detected by the crank angle sensor 401, the fuel injection valve 37 injects the final injection amount set in S5. In S18, when the arrival of the final ignition timing set in S10 or S20 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.

  As described above, in this embodiment, when it is determined that knocking has occurred, the supply amount of the evaporated fuel is reduced. As a result, when knocking occurs, the correction amount for reducing the amount of fuel injected from the fuel injection valve 37 is reduced, and the effect of cooling the intake air due to the latent heat of vaporization of the fuel is improved. Therefore, it is possible to suppress the occurrence of knocking that accompanies a correction for reducing the amount of fuel injected from the fuel injection valve 37 by supplying evaporated fuel.

  In particular, in the case of in-cylinder injection as in the present embodiment, 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, where the influence of the cooling effect of the intake air is greatly reduced by the supply of the evaporated fuel, according to the present embodiment, the occurrence of knocking can be suppressed by correcting the supply amount of the evaporated fuel by reducing the amount of the knocked fuel.

  Further, in the present embodiment, the supply amount of the evaporated fuel is reduced only when it is determined that knocking has occurred and the conditions S11, S12, and S14 are satisfied. Thereby, only when the cause of the knocking is caused by the supply of the evaporated fuel, the supply amount of the evaporated fuel is reduced, and the supply amount of the evaporated fuel can be prevented from being reduced unnecessarily. In this embodiment, when the conditions of S11, S12, and S14 are satisfied, the supply amount of the evaporated fuel is reduced. However, if at least one of these conditions is used, The supply amount of the evaporated fuel may be reduced by satisfying the condition. Furthermore, only the occurrence of knocking may be a condition for reducing the supply amount of the evaporated fuel.

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 driving | running | working area | region which supplies evaporative fuel to the intake passage 6, (b) is a figure which shows the table which calculates the reduction amount correction amount of the purge valve 93.

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 93 Purge valve

Claims (5)

In an engine control device provided with an evaporated fuel supply device for supplying evaporated fuel in a fuel tank to an engine via a control valve,
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;
Correction means for correcting a decrease in the fuel injection amount of the engine in accordance with a supply amount of the evaporated fuel;
Knocking determination means for determining whether knocking has occurred in the engine;
Control valve control means for controlling the control valve so that the supply amount of the evaporated fuel is reduced when it is determined by the knock determination means that knocking has occurred;
A control device comprising: 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 setting means;
The control valve control means includes
Controlling the control valve so that the supply amount of the evaporated fuel is decreased when the knocking determination means determines that knocking has occurred and the index value satisfies a predetermined condition. The control device according to claim 1, wherein The control valve control means includes
When it is determined by the knocking determination means that knocking has occurred, and the operating state of the engine belongs to an operation region predetermined as an operation region in which knocking is likely to occur, the supply amount of the evaporated fuel is The control device according to claim 1, wherein the control valve is controlled to be reduced.   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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